Status Of Redfish Stocks in the Northwest Atlantic: and in Division 3O

Status Of Redfish Stocks in the Northwest Atlantic: and in Division 3O
DFO Science
Stock Status Report A1-01
Q u eb e c
3K
4S
4R
N e w fo un dla n d
3L
4T
3Pn
Prince Edward
Island
N ew
B run s w ic k
4Vn
3Ps
U .S.A
Status Of Redfish Stocks in the
Northwest Atlantic:
Redfish in Units 1, 2, and 3,
and in Division 3O
5Y
3O
4W
4X
4Vs
3N
Figure 1. Map of the Northwest Atlantic.
Background
Redfish assessments have been reviewed at zonal
meeting since 1995. Following the redefinition of
redfish management units in 1993, it became evident
that these various management units were closely
linked, and that there was a need to co-ordinate the
research and the assessment of these resources.
Redfish Overview
Redfish, also known as ocean perch or
rosefish, belongs to a group of fish that are
commercially exploited in both the Atlantic
and Pacific Oceans. They occur on both
sides of the Atlantic Ocean in cool waters (3°
to 8° C) along the slopes of fishing banks
and deep channels in depths of 100-700 m.
In the west Atlantic, redfish range from
Baffin Island in the north to waters off New
Jersey in the south.
Three species of redfish are present in the
Northwest Atlantic (Sebastes mentella, S.
fasciatus and S. marinus (=S. norvegicus)).
These three species are similar and are nearly
impossible to distinguish by their appearance.
They are not separated in the fishery, and
they are managed together. Except for the
area of the Flemish Cap, S. marinus is
relatively uncommon, and there is a
geographic cline for S. mentella and S.
fasciatus. S. mentella is the only species in
the far north (Davis Strait) and S. fasciatus is
the only species in the south (Gulf of Maine).
In the intermediate areas, a mixture of the
two is found, with S. mentella generally
distributed deeper than S. fasciatus. The
October 1997
Redfish Stocks
these different management areas to varying
degrees since the late 1940s. The most
commonly fished areas have been
Subarea 2 + Division 3K, as well as Units 1,
2 and 3.
exception to this general trend is the Gulf of
St. Lawrence where S. mentella dominates.
Redfish are slow growing and long lived.
Specimens have been aged to at least 80
years. S. fasciatus is a smaller size at a
specific age than S. mentella. Growth is
usually faster in southern areas than in
northern areas, and females grow faster than
males.
On
average,
redfish
take
approximately 8 to 10 years to reach
commercial size (25 cm or 10 inches).
Assessment and management strategies
employed for redfish stocks have been the
same as those applied to other groundfish.
Reference levels were based on F0.1 (12%
exploitation rate) and FMAX (24%) or MSY
(maximum sustainable yield) and 2/3 the
effort at MSY.
Based on previously published information
(Ni and Sandeman 1984), the average length
at which 50 % of female redfish on the
continental slopes in divisions 3O, 3P, 4R,
4S, 4T, 4V, 4W and 4X are mature is about
27 cm (10.5 inches), ranging from 24.4 cm
(9.6 inches) in 4W to 29.6 cm (11.7 inches)
in 3P.
A minimum legal fish size of 22 cm was
introduced in redfish fisheries, first in 1995 in
Divsion 3O, and in 1996 to the other
management areas.
Because of their biology, the pattern of
recruitment, and the presence of two or three
species currently indistinguishable on a
routine basis, management strategies and
tools developed for other groundfish are not
easy to apply and may not be appropriate for
redfish. There is a need to develop new
approaches, specific to redfish, to better
understand and manage these stocks.
Unlike many other fish species, fertilisation
in redfish is internal and females bear live
young. Mating occurs in the fall and females
carry the developing young until the spring
when they are released from April to July. In
all areas examined, Sebastes mentella release
their young a month earlier than S. fasciatus.
In recent years, with the decline of other
groundfish, many sectors of industry have
shown a renewed interest in redfish. This
was particularly true in the Gulf of St.
Lawrence (Unit 1), off Newfoundland’s
south coast (Unit 2) and in the Scotian Shelf
area (Unit 3). Although Division 3O has
been traditionally avoided because of small
fish, interest in fishing this area increased as
well.
Recruitment success in redfish is extremely
variable, and significant year-classes have
been observed at intervals from 5 to 12 years
apart.
In addition to being found near the bottom,
redfish are often distributed well up in the
water column. Fisheries take place using
both bottom and mid-water trawls.
At present, there are eight (8) redfish
management areas in the Northwest Atlantic:
Subarea 2 + Division 3K, Divisions 3LN,
Division 3O, Division 3M (Flemish Cap),
Unit 1 (Gulf of St. Lawrence), Unit 2
(Laurentian Channel), Unit 3 (Scotian Shelf)
and Gulf of Maine (Subarea 5). Except for
the Flemish Cap and the Gulf of Maine,
Canada has prosecuted redfish fisheries in
Industry has expressed a great deal of
concern about the status of these redfish
resources. Questions of stock structure,
recruitment, assessment, and management
approaches have been identified by
stakeholders as the major issues, This has led
to the establishment of a joint DFO/Industry
-2-
Redfish Stocks
Multidisciplinary Research Programme on
redfishes in these areas.
What follows includes information specific to
four redfish stocks (Units 1, 2, 3, and
Division 3O). It was prepared at a meeting
of a zonal working group of redfish scientists
held in Moncton during October 14-16 1997.
Redfish assessments were updated following
the completion of the 1997 summer
groundfish surveys on the Scotian Shelf
(conducted by the Maritimes Region), in the
Laurentian Channel (Newfoundland Region)
and the Gulf of Saint Lawrence (Laurentian
Region).
Members of industry participated in the
reviews of the redfish stocks, and
contributed significantly to the interpretation
of data that were presented during the
meeting. However, they expressed concerns
about the fact that all redfish assessments
were heavily dependant on abundance
estimates from a single research survey time
series.
For more information
Ni, I-H., and E.J. Sandeman. 1984, Size at
maturity of Northwest Atlantic redfishes
(Sebastes). Can. J. Fish. Aquat. Sci
41:1753-1762.
-3-
Laurentian Region
Unit 1 Redfish
Gulf of St, Lawrence Redfish Stock
Stock de Sebastes du
Golfe du
, Saint-Laurent
Unit 1 / Unité 1
Unit 1 Redfish
Background
4R
4S
Redfish in the Gulf of St. Lawrence was previously
managed as Divisions 4RST. In 1993, Divisions 3Pn
and 4Vn , from January to May, were included in the
management unit to take into account the winter
migration of redfish in these areas.
3K
4T
3Pn
4Vn
3Ps
3L
3O
3N
5Y
The directed redfish fishery in Unit 1 was closed in
1995 due to low stock abundance and the absence of
significant recruitment since the early 1980.
4X
5Zc
5Xe
4Vs
4W
,
All Year / Toute l'année
January-May / janvier-mai
The Fishery
The redfish fishery in the Gulf of St.
Lawrence has been characterized by two
periods of high exploitation; the first one at
the beginning of the 1970s and the second in
the 1990s (Figure 2). These two periods are
closely linked to the recruitment of strong
year-classes. Following these peaks, landings
dropped rapidly. For the most recent years,
landings have decreased from 77, 000 t in
1992 (old management units) to about
19,500 t in 1994. The TAC for Unit 1
redfish was set at 60,000 t in 1993 and
reduced to 30,000 t in 1994. The directed
redfish fishery in Unit 1 was closed in 1995
due to low stock abundance.
Landings (thousand tonnes)
Year
70-76
Avg.
TAC
Can.
79
Others
3
Totals
82
1
Provisional
-4-
77-92
Avg.
37
0
37
1993
19941
19951
19961
1997
60
51
0
51
30
19
0
19
0
0
0
0
0
0
0
0
0
Laurentian Region
Unit 1 Redfish
140000
Étrangères/Foreign
120000
Canada
Prises/Catches (t)
TAC Unité/Unit 1
100000
TAC 4RST
80000
60000
40000
20000
0
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Années/Years
< 5
Figure 2. Landings and TACs in tons.
Since 1990, stratified-random groundfish
surveys have been conducted in 4RST in
August-September on the Alfred Needler.
The biomass index from these surveys has
been declining from 1990 to 1996 (Figure 3).
In 1997, the index increased slightly but
remained at a low level.
< 5 00
< 10 00
> 10 00 kg /tra it-t ow
the fishery catches in the late 1980s and at
the beginning of the 1990s. Surveys indicate
that the 1988 year-class declined rapidly
after 1991 and from 1994, it has almost
disappeared from survey catches, for reasons
that remain unclear, prior to contributing to
the commercial catches.
During the period of decline, the distribution
of redfish became more restricted and
concentrations are mainly found now in the
Cabot Strait area (Figure 4). Also, in 1997,
the highest catch of the survey was observed
north of Anticosti Island.
Five sentinel surveys targeting 4RS3Pn cod
have been conducted by small otter trawlers
since August 1995. Three of these surveys
were conducted in the summer (July and
August) when Unit 1 redfish are within
Divisions 4RST. These surveys could
provide information on Unit 1 redfish. The
other two surveys were conducted in the fall
(November 1995 and October 1996), when
the migration of Unit 1 redfish at the
entrance of the Gulf might has started.
Numbers at length from the summer surveys
(Figure 5) for the period 1990 to 1997
indicate the presence of only two important
modes, corresponding to the 1980 and 1988
year-classes. The 1980 year-class dominated
Poids moyen/Mean weight (kg)
< 1 00
Figure 4. Redfish catch distribution on
research vessel survey in August 1997.
Resource Status
70
In order to standardize the various vessels
participating in the surveys, several
modifications have been made to the gears
used in the sentinel surveys. These early
adjustments to the design of these surveys
make the inter-year comparisons difficult.
60
50
40
30
20
10
0
1990
< 20
1991
1992
1993
1994
1995
1996
1997
Catch rate from the fall sentinel surveys
were much lower than in the summer sentinel
surveys. This difference could be accounted
for by a combined effect of movement of
Années/Years
Figure 3. Research vessel survey biomass
index.
-5-
Laurentian Region
Unit 1 Redfish
survey may be measuring both reduced
abundance
and
earlier
migration.
Nonetheless, the reduction in abundance in
the early 1990s was clearly substantial.
1998
1997
Industry perspectives
1996
1988 year-class
Given that the Unit 1 fishery has been closed
since 1995, industry representatives had no
direct information regarding the state of the
stock. However, those involved in the cod
sentinel surveys indicated that redfish were
more wide spread in the Gulf in the summer
of 1997 than in 1996. Also, some
participants indicated that larger fish were
caught in 1997 surveys than in 1996.
Année/Year
1995
1994
1993
1992
1991
They were also concerned that the
abundance and distribution information is
mainly coming from one survey. This could
limit the possibility to describe changes in
movements and distribution that may have
occured in recent years.
1980 year-class
1990
0
5
10
15
20
25
30
35
40
45
50
Longueur/Length (cm)
Figure 5. Size compositions from
summer research survey (1990-1997).
the
Outlook
The abundance index from the summer
research survey is still at a low level. At this
time there is no sign of any significant
incoming recruitment and the stock will
remain at a low level.
redfish in the Cabot Strait area and changes
in the seasonal availibility of redfish to
bottom trawl. Length frequencies from all
the sentinel surveys showed that larger fish
were caught in the fall surveys.
For further information
A comparison of the sentinel surveys and
research surveys shows that the distribution
of catches in early years of the research
surveys were similar to those seen in JulyAugust sentinel surveys, but, from 1993,
distributions were more similar to OctoberNovember
sentinel
surveys.
Size
compositions in recent research surveys were
also more similar to those in the OctoberNovember sentinel surveys than those
conducted
in
July-August.
Industry
participants indicated that, in their view,
seasonal migration out of the Gulf occurred
progressively earlier in the years immediately
prior to fishery closure. Thus, the research
Morin, B. and B. Bernier 1997. The status
of redfish in Unit 1 (Gulf of St.
Lawrence). DFO Atl. Fish. Res. Doc.
97/112.
Prepared by
Bernard Morin
Institut Maurice-Lamontagne,
POB 1000, Mont-Joli,
Québec, G5H 3Z4
Tel:(418)775-0695
Fax:(418)775-0740
E-Mail: morinb@dfo-mpo.gc.ca
-6-
Newfoundland Region
Unit 2 Redfish
Laurentian
, Channel Redfish Stock
Stock de Sébaste
du
,
chenal Laurentien
,
Unit 2 / Unité 2
Unit 2 Redfish
3K
Background
The Unit 2 management unit for redfish was
implemented in 1993. The resource in this area
(NAFO 3Ps4Vs, 3Pn4Vn-June to Dec., 4Wfgj) were
previously managed separately as a 3P stock and
part of a 4VWX stock, The change was recommended
in 1991, based on a detailed examination of
available data that suggested that a realignment in
the existing management units was warranted to
better represent what was known about redfish in
these areas.
4R
4S
4T
3Pn
4Vn
3L
3Ps
3O
3N
5Y
4Vs
4X
4W
5Zc
5Xe
,
All Year / Toute l'année
,
June-December / juin-décembre
The first quota for Unit 2 in 1993 was 28,000 t.
Since then TACs have been reduced successively to
10,000 t for 1996 as a conservation measure and
was maintained at that level for 1997. In 1995
area/season closures were implemented to (i)
minimise possible overlaps with Unit 1 redfish given
a lack of understanding of redfish migration patterns
and (ii) allow for a period when peak spawning of
females is likely to occur. A small fish protocol at
25 cm (10 inches) was imposed for 1996 aimed at
protecting the 1988 year-class as it appears this may
be the major contributor to the fishable population
in the near future given the current exploitation
pattern in the fishery. In 1997 the small fish protocol
was reduced to the standard 22 cm for redfish.
The Fishery
From 1960 to 1968, landings were about
20,000 t. Landings increased to an average
of 43,000 t up to 1975 mainly due to
increases by foreign fleets, then subsequently
declined to the lowest on record in 1984 at
8,100 t. Catches then steadily increased to
27,000 t in 1993 and have declined
subsequently to 9,000 t in 1996; matching
reductions in TACs (Figure 6). Up to the
beginning of October 1997, about 9,000 t of
a 10,000 t TAC had been taken.
The implementation of this new management unit in
1993 resulted in a change in the fishing pattern from
that generally in place under the old 3P, 4RST and
4VWX units, There was a 10,000 t increase from the
1992 catch of about 17,000 t and this was almost
totally accounted for by landings from 3Pn during
the last quarter of the year. Based on information
presented to the Fisheries Oceanography Committee
of DFO, Science in March, 1994 these catches were
probably of Unit 1 redfish which moved into the
area earlier in 1993. Although relatively large
catches did not occur in these adjacent subdivisions
in 1994, possible overlaps with Unit 1 fish in
3Pn/4Vn during November and December were
cause for concern, given that Unit 1 is at a very low
level (under moratorium from 1995-1997).
Subsequently 3Pn/4Vn has remained closed in
November and December since 1994.
Landings (thousand tonnes)
Year
TAC
70-76 77-92 1993 19941 19951 19961 1997
Avg. Avg.
-
-
25
14
10
10
28
Can.
17
16
27
24
12
9
Others
15
1
0
0
0
0
Totals
32
17
27
24
12
9
1
Provisional
Since declaration of the 200 mile limit in
1977, catches have been primarily by
Canadian fleets. Maritimes vessels have
generally accounted for the majority of
landings from subdivisions 4Vs and 4Vn
-7-
Newfoundland Region
Unit 2 Redfish
30000
1.2
25000
Standardized Catch Rate (t/hr)
Foreign
Canada
TAC
20000
15000
10000
1
0.8
0.6
0.4
0.2
1996
1993
1990
1987
1984
1981
1978
1975
1972
1969
1966
1960
1963
0
5000
Year
0
82
Figure 6.
tons).
84
86
88
90
92
94
96
Figure 7. Standardized commercial catch
rate of vessels directing towards redfish in
Unit 2 (in tons per hour).
Reported catches and TACs (in
whereas Newfoundland vessels concentrated
in subdivisions 3Ps and 3Pn.
coincided also with the introduction of major
changes in fishing technology. The
suddenness of this event is not understood,
and the changes in catch rates from 1988
cannot be interpreted in relation to
abundance of the stock.
In 1996, over half of the 9,000 t catch had
been taken in the first quarter and primarily
from 3Ps. About 2,500 t of this had been
taken in statistical area 3Psd, adjacent to
3Pn. In 1997, over 90% of the TAC has been
taken up to Oct. 1 primarily in the first
quarter and the majority of which was again
taken in 3Ps.
Resource Status
Indices of Stock Size
The most valuable information used to assess
this stock comes from research surveys
conducted in subdivisions 3Ps, 3Pn, 4Vs and
4Vn during the summer from 1994-1997.
The summer is when redfish in this area are
considered to be most separated from Unit 1
fish. The biomass index (thousands of
metric tons) from these surveys is :
Sampling of the fishery in recent years
suggests the majority of the catch was
comprised of fish between 28 cm (11 inches)
to 33 cm (13 inches), the bulk of which is
likely the early 1980s year-class. The 1988
year-class was present in the catches in 1994,
1995 and 1997 but to a lesser extent in 1996.
This was likely because of the effect of the
higher small fish protocol at 25 cm in 1996
compared to 22 cm in 1997.
Index
In earlier years, fluctuations in the
standardized commercial catch rate series
(Figure 7) agree with recruitment of major
year classes in the fishery. However, there
was a brief but major increase in CPUE
centered around 1990 that cannot be
explained by the biology of redfish alone.
This peak is associated with the recruitment
of the 1980s year class(es) to the fishery but
1994
1995
1996
1997
239
209
196
214
The summer survey results suggest that
stock size remained stable at about 200,000 t
between 1994 and 1997, slightly below the
1994 level. As the survey was conducted by
a shrimp trawl, which samples pre-recruits,
an exploitable biomass index was calculated
by applying selectivity curves corresponding
-8-
Newfoundland Region
Unit 2 Redfish
Unit 2 resource. Each survey covers only
part of the entire area where the resource
occurs. This makes it difficult to interpret
apparent trends over time because they may
not be reflective of changes occurring
throughout the entire management unit but
may reflect movement into and out of the
surveyed areas. Nonetheless, these series are
consistent with the Unit 2 survey in terms of
size composition and general trend.
1998
1997
1996
1995
Industry Perspectives
Because of the change in fishing pattern that
resulted from the implementation of this
management Unit in 1993, as well as the
regulation in 1995 of seasonal closures (in
May-June for all of Unit 2 and NovemberDecember for 3Pn and 4Vn) and the small
fish protocol, the major stakeholders in the
fishery cannot relate their past experiences to
the current situation.
1994
1993
0
5
10
15
20
25
30
35
40
45
50
Length
Figure 8. Number at length of redfish from
the research survey in Unit 2.
The 1996 fishery had been conducted
primarily in areas 3Psd and 4Vsc with one
stakeholder experiencing a substantial
increase in catch rate compared to 1995.
This increase was the result of the detection
of a relatively large body of fish in 3Psd
during the first quarter of the year, Fish were
large in this area and the small fish protocol
was not restrictive One other stakeholder
also experienced similar catch rates and fish
sizes but was concerned about the recent
recurrence of the parasite problem.
to the commercial fishery. This results in an
exploitable biomass index of about
100,000 t.
The length compositions from these surveys
(Figure 8) were dominated by two modes,
the peaks of which were 23-24 cm (about
9 inches), corresponding to the 1988 year
class and 31-33 cm (about 13 inches),
corresponding to the early 1980s year
class(es) in 1997. The 1997 survey also
indicates a relatively strong abundance of
fish at 12 cm (about 5 inches), corresponding
to the 1994 year class, that was primarily
caught in 3Pn. Although the estimated
abundance index of the 1988 year-class in
the 1997 survey was higher than in the 1996
survey, it does not appear to be as abundant
as it was in the 1994 and 1995 surveys.
The 1997 fishery to date was generally
conducted in a similar pattern as the 1996
fishery and was considered by some to be as
good or better than 1996. It was noted that
most of the difficulties were related to bad
weather rather than the fishery. One
stakeholder related that fish sizes were
generally larger in 3Psd than 4Vsc and had
more parasites.
Three other stratified-random groundfish
surveys are available up to 1997 but are of
limited value in determining the status of the
-9-
Newfoundland Region
Unit 2 Redfish
Outlook
Prepared by
Don Power
Northwest Atlantic Fisheries Centre
Fisheries and Oceans
POB 5667
St. John’s, Newfoundland
A1C 5X1
Tel
(709) 772-4935
Fax.
(709) 772-4188
e-mail:
Power@athena.nwafc.nf.ca
An estimate of exploitable biomass from the
summer survey of about 100,000 t indicates
that a catch of 10,000 t in 1998 would
generate an exploitation rate of about 10%.
The survey results provide minimum
estimates of exploitable biomass so the
actual exploitation rate is likely to be lower
that 10%. Therefore, a catch in 1998 of
10,000 t is not likely to be higher than the
catch associated with fishing at F0.1.
Current commercial catches are composed
primarily of the early 1980s year-class(es)
which have been fished for about eight years.
The next anticipated pulse of recruitment
(the 1988 year-class) is now becoming more
fully recruited to the fishery. However, its
contribution to the fishable stock will not be
as great as that of the early 1980s year
class(es).
A pulse of pre-recruits was observed in the
1997 survey at 12 cm (about 5 inches),
corresponding to the 1994 year class. This
pulse is much larger than any other observed
after the 1988 year class. Its potential will
require a few years of monitoring before its
relative strength can be related to other year
classes comprising the commercial fishery. In
any case, its contribution will not be fully
realized in the fishery for at least another 710 years.
For Further Information
Power, D., and D. Orr. 1996. The status of
Redfish in Unit 2 (Laurentian Channel
Management Unit). DFO Atl. Fish. Res.
Doc. 97/113.
- 10 -
Maritimes Region
Unit 3 Redfish
SW Scotia
, Shelf Redfish Stock , ,
Stock de Sébaste
, , du
plateau, Néo Écossais
Unit 3 / Unité 3
Unit 3 Redfish
Background
4R
4S
The Unit 3 management area for redfish was first
implemented in the 1993 Groundfish Management
Plan with a quota of 10,000 t. Redfish in this area
were previously managed as part of a larger 4VWX
management area.
3K
4T
3Pn
4Vn
3L
3Ps
3O
5Y
Redfish in Unit 3 are primarily caught in the basins
and at the edge of the Scotian Shelf by otter trawlers
using 90 mm mesh. Regulations limit the bycatch in
NAFO Division 4X of other groundfish species to
10 % by weight of redfish caught and the bycatch in
NAFO divisions 4VW to 2 % by weight each of cod
and haddock.
3N
4Wdehkl
4Vs
4X
4W
5Zc
5Xe
The Fishery
Starting in 1995, the Scotia-Fundy summer
groundfish survey, which is the primary source of
population and size composition data for this stock
was enhanced to include redfish species
identification techniques and extended to 400
fathom in order to cover redfish habitat at the shelf
edge previously not covered by the survey. Size
composition of fish taken there are now beginning to
explain differences between the survey and the
commercial fishing results in the area.
Landings (thousands of tonnes)
Year
70-79 80-89 90-92 932 942 952 962 97
avg
avg
avg
TAC
10.0 10.0 10.0 10.010.0
Canada
4.1
4.4
2.2
5.1 5.2 4.9 4.7
Foreign
1
5.7
0.5
0.1
0.2
Total
9.7
4.9
2.3
5.3 5.2 4.9 4.8
1
2
+
+
+
1970-79 foreign landings exclude up to 4,420 t/yr on
average not assignable to statistical unit area
Provisional
Redfish landings from Unit 3 (Figure 9)
gradually increased from the late 1970s,
peaking at almost 7,000 t in 1986, followed
by a decline to about 2,000 t in 1991.
Provisional catches for 1996 were about
4,800 t, slightly less than in 1993-95 and well
below the 10,000 t TAC. The provisional
Canadian catch for January through July
1997 was about 3,200 t, somewhat more
than for the same time period in 1996 (2,700
t).
- 11 -
Maritimes Region
Unit 3 Redfish
Unit 3 redfish landings have traditionally had
a high proportion of fish in the 20-25 cm
range. However catches of fish less than this
size were rare. Increased catches of fish less
than 20 cm in 1994-95 resulted in a portion
of 4Xo known as the ‘Bowtie’ being closed
to fishing from late May of 1995 (at
industry’s request) and for a 22 cm minimum
fish size to be included in the Conservation
Harvesting Plans for 1996. Percentages by
number of redfish landings from combined
port and observer samples under this size
were:
12
Fgn
Cdn
TAC
10
8
6
4
2
0
77
79
81
83
85
87
89
91
93
95
Figure 9. Canadian, foreign landings and
TACs (in thousands of tons)
In 1996, small otter trawlers (less than 65 ft),
fishing in the basins, took most of the
reported catch. Large otter trawlers (greater
than 65 ft) fishing in the basins and at the
edge of the shelf, took only a very small
portion of the catch (Figure 10). In early
1997 (to July), small otter trawlers began to
catch large redfish on grounds deeper than
200 fathoms at the shelf edge. Landings of
smaller redfish from 4Xo and basins to the
east were much less than for this period in
1996. Large otter trawlers took almost no
redfish in this period.
% < 22 cm
94
95
96
97
(to July)
3.5
14.8
15.1
10.3
6.9
The proportions of small redfish were higher
in catches from 4Xo, where most of the
small redfish occur as shown from research
surveys, than for other areas of Unit 3
(Figure 11).
5
10
4WdehkXm
7
4WlXn
Other
TC4+5
TC2+3
6
93
15
20
25
30
35
40
45
50
Commercial Catch
Research
Survey
22 cm
(includes > 200 fm)
4Xo
5
4Xpqrs
4
Unit 3
3
2
Figure
11.
Research
(solid)
and
commercial (dotted) size composition (cm)
by area for 1995-97 (%).
1
0
77
79
81
83
85
87
89
91
93
95
Figure 10. Canadian landings by vessel
type (in thousands of tons)
In addition to using bycatch trip limits, a
number of areas were closed to redfish
fishing in 1996 to further limit bycatch.
Landings statistics for 1996 indicated that
- 12 -
Maritimes Region
Unit 3 Redfish
fishery make commercial catch rates
impossible to interpret in the context of
redfish abundance.
7
6
5
Survey estimates of population biomass (less
than 200 fathoms), are highly variable
between years and show no trend since the
late 1980s (Figure 13). In recent years, there
has been evidence that there are more small
fish, particularly in the area north and east of
Brown’s Bank. A large proportion of these
small fish are now between 20 and 22 cm
long (Figure 6).
4
3
2
1
0
Pollock
Cod
White
hake
Haddock
Cusk
Flatfish
Figure 12. Bycatch by species for 1996
(%).
250
pollock accounted for most of the bycatch in
Unit 3 (Figure 12). The highest rates for all
species combined were in the west (4Xpq),
but neither industry nor management
consider the situation there to be a problem
because most of the bycatch consisted of
legal sized fish and was counted towards the
vessels’ quota of these species.
total
< 22 cm
< 20 cm
200
150
100
50
0
82
Resource Status
50
0
88
90
92
94
90
92
94
96
The ratio of recent catch tonnages to total
survey biomass gives an estimate of
exploitation rate of less than 10 percent.
Total survey biomass was used for this
calculation without adjustment as survey and
commercial catch size compositions usually
do not differ greatly. However, survey
biomass is considered a conservative
estimate of actual exploitable biomass and
thus the calculated exploitation rate is
thought to be an upper estimate.
100
86
88
The 1997 abundance estimate is much higher
than earlier values but that this is, at least in
part, a reflection of higher catch-ability to
the survey in that year.
150
84
86
Figure 14. Survey numbers per tow by size
class.
The increase in catches in 1993, compared
to 1988-92, resulted from an increase in
fishing effort by small otter trawlers,
reflecting decreased fishing opportunities for
more valuable species, and not an increase in
redfish abundance. The many changes in this
82
84
96
Figure 13. Biomass index from summer
survey (in thousands of tons)
- 13 -
Maritimes Region
Unit 3 Redfish
Industry Perspectives
For Further Information
Large otter trawler owners claim that they
are increasingly unable to operate due to
conflicts with fixed gear and to high bycatch
levels as well as high proportions of small
fish in the catches. Small otter trawler
captains and plant operators in Southwest
Nova Scotia are pleased with the catches of
large redfish at the shelf edge but are
concerned about the smaller redfish
elsewhere. There were reports of small
redfish being landed after the July opening of
Brown’s Bank to small mesh gear in the area
immediately south of the ‘Bowtie’ in both
1996 and 1997. Industry processing records
confirm that biological sampling does not
fully reflect the landings of small fish from
this area during this period. Industry also
note a lack of DFO enforcement of the 22
cm small fish protocol in 4X but claim some
self-regulation of the catching of fish less
than 20 cm. Most operators advocate that
these small fish should be avoided through
modification of the closed area boundaries
and/or a system of test fishing.
Annand, C., Hansen, J. 1997. Management
Activities for 1995 and early 1996
Scotia Fundy Region, DFO Atl. Fish.
Res. Doc. 97/114.
Branton, R. 1997 Update on the Status of
Unit 3 redfish: 1997. DFO Atl. Fish.
Res. Doc. 97/103.
Branton, R. and J. Black 1997. 1997
Summer Groundfish Survey Update for
Selected Scotia-Fundy Groundfish
Stocks: 1997. Res. Doc. 97/104.
Prepared by
Robert Branton
Marine Fish Division
Bedford Institute of Oceanography
1 Challenger Drive, Dartmouth
Nova Scotia, B2Y 4A2
TEL
(902) 426-3537
FAX
(902) 426-1506
Email: brantonb@mar.dfo-mpo.gc.ca
Outlook
Research vessel surveys indicate stability in
the population biomass with improved
recruitment particularly in and around 4Xo.
However, it is not yet clear to what extent
this recruitment will increase exploitable
biomass and hence improve fishing success.
TACs for Unit 3 redfish of 10,000 tons,
when compared to survey biomass estimates,
correspond to an exploitation rate of about
15 percent. As survey biomass estimates are
considered
underestimates of actual
biomass, a catch of 10,000 tons is not likely
to exceed that corresponding to F0.1 in 1998.
- 14 -
Newfoundland Region
Division 3O Redfish
NAFO Div.
, 3O Redfish Stock
Stock de Sébaste
de la Division 3O de l'OPANO
Division 3O Redfish
3K
Background
4S
Traditionally, Canadian industry has not had a great
deal of interest in redfish in this area because of the
relatively small sizes of fish found in the areas with
trawlable bottom. Recently, because of declines in
other resources and developing markets for small
redfish for lobster bait, there has been some
increased interest in fishing in this area.
4T
3Pn
4Vn
3L
3Ps
3O
4Vs
4X
4W
5Zc
5Xe
A TAC of 16,000 t was first implemented on this
stock in 1974. The TAC was increased in 1978 to
20,000 t. The TAC for 1988 was reduced to 14,000 t
and remained unchanged until 1994 when it was
reduced to 10,000 t as a precautionary measure and
maintained at that level to 1997.
3N
The Fishery
Nominal catches have ranged between 3,000 t
and 35,000 t since 1959 (Figure 15). Up to
1986 catches averaged 13,000 t, increased to
27,000 t in 1987 with a further increase to
35,000 t in 1988, exceeding TACs by 7,000 t
and 21,000 respectively. Catches declined to
13,000 t in 1989, and were about this amount
annually through to 1993. The 1994 catch, at
about 5,400 t, represented an 11,000 t
reduction from 1993. Catches declined further
to about 3,000 t in 1995 but increased to
9,000 t in 1996 due to activity by various
Canadian enterprises.
In addition to catch regulation, a small fish protocol
at 22 cm was implemented inside the 200 mile limit
for this stock in 1995. The current TAC (10,000 t) is
divided into a Canadian quota (5,590 t), a French
(St. Pierre et Miquelon) quota (1,500 t) and a
Foreign Quota (2,910 t).
About 10% of the stock area lies outside Canada’s
200 mile Exclusive Economic Zone (EEZ).
Landings (thousand metric tons)
Year
TAC
Can.
70-76 77-92 1993 19941 19951 19961 1997
Avg. Avg.
-
-
14
10
10
10
10
2
1
1
1
2
.1
7
Others
13
14
15
4
3
2
Totals
14
15
16
6
3
9
1
Provisional
Russia predominated in this fishery until
1993, but had much lower catches in 1994
and 1995 and no effort in 1996. Cuba has
not participated in the fishery in this area
since 1993. Portugal, which began fishing in
- 15 -
Newfoundland Region
Division 3O Redfish
greater than 25 cm with modes at around 30
cm. The 1996 Portuguese catches showed a
much broader range of lengths from about
25 cm to 42 cm with modes at 30 cm and 38
cm.
35000
Catch (tons)
30000
25000
20000
A standardised catch rate index using
Canadian data only, and based on effort in
hours fished, shows much inter-annual
variability over the 1959-1996 period but
without any discernible trend with time.
Previous analyses of catch rate data from
foreign fleets fishing the area outside
200 miles have indicated declines in recent
years.
15000
10000
5000
0
1960
1966
1972
1978
1984
1990
1996
Year
Canadian
Others
TAC
Figure 15. Reported catches and TACs of
redfish from Division 3O (in tons),
Resource Status
the area in 1992, took 2,900 t in 1994 and
about 1,800 t in each of 1995 and 1996.
Russia, Cuba and Japan fished throughout
the stock area after extension of jurisdiction
through agreements with Canada. Other nonCanadian catches including those of Portugal
were taken in the limited stock area outside
200 miles.
Stratified random groundfish surveys
have been conducted in the spring and fall in
Division 3O since 1991, with coverage to
depths down to 730 m. Beginning in the fall
of 1995, the survey gear was changed from
the Engel trawl to a Campelen shrimp trawl,
This new gear has a similar catchability for
large redfish, but a much greater catchability
for very small redfish.
Canada, which has had limited interest in a
fishery in this area because of the small sizes
of redfish encountered, landed less than 200 t
annually from 1983-1991, took 1,600 t in
1994, but their catches declined to only
about 100 t in 1995. Canadian catches have
increased dramatically in 1996 to about
7,000 t. About 2,000 have been taken by
Canada to Oct. 1 in 1997. The fishery has
occurred primarily in the second and third
quarters of the year since 1983. The 1996
Canadian catch was taken from September to
December. The predominant means of
capture from the mid-1970s to the early
1980s was the bottom otter trawl. Since
1984, there has been an increase in the use of
midwater trawls although bottom trawl
catches still dominate.
Survey Biomass Index
140000
120000
Spring
Fall
100000
80000
60000
40000
20000
0
1991 1992 1993 1994 1995 1996 1997
Figure 16.
Research survey index for
Division 3O redfish.
The spring survey index (Figure 16)
increased steadily from 1992 through 1996
but declined sharply in 1997. Stratum by
stratum estimates indicate that the increases
Length frequency information from the 1996
fishery indicated a preponderance of fish
- 16 -
Newfoundland Region
Division 3O Redfish
during the spring surveys occurred over a
great deal of the area, although in the spring
of 1996 only a few large sets were
responsible for the observed increase.
available to some Canadian enterprises
suggests that water temperature influences
fishing success. So far in 1997, there were
reports of much greater mixtures of small
fish with the large fish in the area and there
are indications that catch rates are lower than
1996. This fishery is still considered to be in
the learning stage.
The fall survey index increased gradually
from 1991 through 1993 but declined slightly
in 1994 before increasing significantly in
1995. The index declined sharply in 1996 but
the extent of the decline is unknown because
four important strata were not sampled.
Outlook
It is still not possible to describe overall
trends in total stock size, or estimate the
current size of the fishable portion of the
population, nor is possible to determine
current fishing mortality rate. On the
assumption that the pre-recruits measured by
the survey in recent years have now largely
passed through the size ranged measured by
these surveys but remained in Div. 3O, they
represent an addition to the exploitable stock
of about 100,000 t. Thus, catches of about
10,000 t are not likely to generate fishing
mortality above F0.1.
The surveys catch fish in the 10 cm to 25 cm
range whereas the commercial catch is
mostly comprised of fish greater than 25 cm.
Given that the surveys are not measuring the
main portion of the stock exploited by the
fishery, recent declines in the survey
estimates therefore, do not appear to be
related to fishing. The surveys only monitor
pre-recruit size groups and while the recent
declines should be viewed with concern, it is
difficult to interpret these events in relation
to what is happening to the stock as a whole.
There is also some concern that there has
been little sign in the recent surveys of size
groups smaller than 17 cm despite using a
shrimp trawl which is very effective at
catching small fish.
For Further Information
Power, D., and D. Orr. 1997. Update on the
status of redfish in Division 3O . DFO
Atl. Fish. Res. Doc. 97/115.
In all surveys, the biomass indices in strata
outside 200 miles were low compared to
those inside.
Industry Perspectives
The increased activity in 1996 for some
Canadian enterprises was motivated by a
need to find fish of marketable size in light of
the moratorium in Unit 1 and was based on
the premise that there were larger fish in
deeper water in Div. 3O. The experience of
this fishery was different from other
Canadian fisheries but there was reasonable
success in finding good concentrations of
acceptable size fish, primarily from October
to December. The knowledge from the
Russian fishing experience in the area
- 17 -
Newfoundland Region
Division 3O Redfish
Prepared by
Don Power
Northwest Atlantic Fisheries Centre
Fisheries and Oceans
POB 5667
St. John’s, Newfoundland
A1C 5X1
Tel.
(709) 772-4935
Fax.
(709) 772-4188
e-mail: Power@athena.nwafc.nf.ca
! " #$
$%%
" " "
! - 18 -
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