West Coast of Newfoundland Atlantic Herring (Division 4R)

Similar documents
West Coast of Newfoundland Atlantic Herring (Division 4R)

ASSESSMENT OF THE WEST COAST OF NEWFOUNDLAND (DIVISION 4R) HERRING STOCKS IN 2011

ASSESSMENT OF THE WEST COAST OF NEWFOUNDLAND (DIVISION 4R) HERRING STOCKS IN 2013

ASSESSMENT OF HERRING IN THE SOUTHERN GULF OF ST. LAWRENCE (NAFO DIV. 4T)

Southern Gulf of St. Lawrence (4T) Herring

Southern Gulf of St. Lawrence (4T) Herring

Southern Gulf of St. Lawrence Herring

Cod in the Northern Gulf of St. Lawrence

Gulf of St. Lawrence (4RST) Greenland Halibut

Witch Flounder (Divs. 4RST)

Year Avg. TAC Can Others Totals

Witch Flounder (Divs. 4RST)

HADDOCK ON THE SOUTHERN SCOTIAN SHELF AND IN THE BAY OF FUNDY (DIV. 4X/5Y)

Northwest Atlantic Harp Seals

Canadian Science Advisory Secretariat Gulf Region Science Advisory Report 2016/036

Map Showing NAFO Management Units

Gulf of St. Lawrence (4RST) Greenland Halibut in 2003

SA2 + Div. 3K Redfish

ATLANTIC SALMON NEWFOUNDLAND AND LABRADOR, SALMON FISHING AREAS 1-14B. The Fisheries. Newfoundland Region Stock Status Report D2-01

TAC Reported Landings * - By-catch only

3.4.3 Advice June Barents Sea and Norwegian Sea Cod in Subareas I and II (Norwegian coastal waters cod)

THORNY SKATE IN DIVISIONS 3L, 3N, 3O AND SUBDIVISION 3Ps

Shrimp of the Estuary and the Gulf of St. Lawrence

Advice June 2014

4.9.5 Norwegian spring-spawning herring

Advice June 2012

SHRIMP OF THE ESTUARY AND GULF OF ST. LAWRENCE IN 2004

Eastern and South Shore Nova Scotia Lobster LFAs The Fishery. DFO Atlantic Fisheries Stock Status Report 96/117E.

NEWFOUNDLAND REGION GROUNDFISH OVERVIEW

10.4 Advice May 2014

Update on Selected Scallop Production Areas (SPA s) in the Bay of Fundy

Capelin in the Estuary and Gulf of St. Lawrence

Pelagic fishery for Sebastes mentella in the Irminger Sea

ASSESSMENT OF SCALLOPS (PLACOPECTEN MAGELLANICUS) IN SCALLOP FISHING AREA (SFA) 29 WEST OF LONGITUDE 65 30'W

Atlantic Mackerel of the Northwest Atlantic

2010 ASSESSMENT OF 4VWX HERRING

10.3 Advice May 2014

Advice May Herring in Subdivisions and 32 (excluding Gulf of Riga herring)

WORKING GROUP ON STOCK ASSESSMENTS 5 TH MEETING DOCUMENT SAR-5-08 TARGET SIZE FOR THE TUNA FLEET IN THE EASTERN PACIFIC OCEAN

9.4.5 Advice September Widely distributed and migratory stocks Herring in the Northeast Atlantic (Norwegian spring-spawning herring)

Shrimp of the Estuary and the Gulf of St. Lawrence

Southern Gulf of St. Lawrence Sea Scallop

ASSESSMENT OF SHRIMP STOCKS IN THE ESTUARY AND GULF OF ST. LAWRENCE IN 2011

3.4 Stock Summaries Advice June 2011

Shrimp of the Estuary and Gulf of St. Lawrence in 2003

Assessment of Atlantic mackerel in subareas 3-4

Baltic Stock Advice. 14 May John Simmonds ICES ACOM Vice Chair

Fish Conservation and Management

2.3.1 Advice May Capelin in Subareas V and XIV and Division IIa west of 5 W (Iceland East Greenland Jan Mayen area).

Advice June, revised September Herring in Division IIIa and Subdivisions (Western Baltic spring spawners)

Spurdog (Squalus acanthias) in the Northeast Atlantic

Technical Briefing. Northern Cod (NAFO Div. 2J3KL) Newfoundland & Labrador March 23, 2018

Iceland Scallop in Newfoundland and Labrador

Dauphin Lake Fishery. Status of Walleye Stocks and Conservation Measures

Trends in Scottish Fish Stocks 2017

Gulf of Maine Research Institute Responsibly Harvested Seafood from the Gulf of Maine Region Report on Atlantic Sea Scallops (Inshore Canada)

ASMFC Stock Assessment Overview: Atlantic Menhaden

Eastern Scotian Shelf Haddock (Div. 4TVW)

The South African and Namibian horse mackerel fisheries Prepared by Dave Japp and Melanie Smith. The South African horse mackerel

Snow Crab of the St. Lawrence Estuary and the Northern Gulf of St. Lawrence (Areas 13 to 17 and 12A, 12B and 12C) in 2002

ICES advises that when the MSY approach is applied, catches in 2019 should be no more than tonnes.

Overview 10/8/2015. October Pelagic Advice Pelagic AC 7 October 2015

ICES Advice on fishing opportunities, catch, and effort Celtic Seas and Greater North Sea ecoregions Published 30 June 2016

Haddock (Melanogrammus aeglefinus) in divisions 7.b k (southern Celtic Seas and English Channel)

17-06 BFT RECOMMENDATION BY ICCAT FOR AN INTERIM CONSERVATION AND MANAGEMENT PLAN FOR WESTERN ATLANTIC BLUEFIN TUNA

Advice June Sole in Division IIIa and Subdivisions (Skagerrak, Kattegat, and the Belts)

Trends in Scottish Fish Stocks 2018

ICES Advice on fishing opportunities, catch, and effort Celtic Seas and Greater North Sea Ecoregions Published 24 October 2017

Map Showing NAFO Management Units

STOCK STATUS REPORT LAURENTIAN REGION. Maurice Lamontagne Institute P.O. Box 1000, Mont-Joli, Québec, G5H 3Z4, CANADA

Report on Biology, Stock Status and Management of Southern Bluefin Tuna: 2017

NORTHERN SHRIMP ON THE EASTERN SCOTIAN SHELF (SFA 13-15)

Sprat (Sprattus sprattus) in subdivisions (Baltic Sea)

REDFISH in Sub-areas I and II. Nominal catch (t) by countries in Sub-area I, Divisions IIa and IIb combined as officially reported to ICES.

North East Atlantic Fisheries Baltic Sprat Whitepaper March 2011

Plaice (Pleuronectes platessa) in Subarea IV (North Sea) and Division IIIa (Skagerrak)

Plaice (Pleuronectes platessa) in Division 7.e (western English Channel)

ASMFC Stock Assessment Overview: Red Drum

STOCK STATUS OF SOUTHERN BLUEFIN TUNA

Advice June Capelin in Subareas V and XIV and Division IIa west of 5 W (Iceland East Greenland Jan Mayen area).

Herring (Clupea harengus) in subdivisions and 32 (central Baltic Sea, excluding Gulf of Riga)

SCIENCE ADVICE ON HARVESTING OF NORTHWEST ATLANTIC HARP SEALS (Pagophilus groenlandicus) IN 2009

Southern Gulf of St. Lawrence Herring Fishery

7/14/2014. ICES advice for herring stocks in Template (as in previous years) State of stock table (as previous years) Advice online

ASSESSMENT OF THE NORTHERN GULF OF ST. LAWRENCE (3PN, 4RS) COD STOCK IN 2014

Atlantic cod, No rthern stock in Newfoundland and Labrador region

Golden redfish (Sebastes norvegicus) in subareas 5, 6, 12, and 14 (Iceland and Faroes grounds, West of Scotland, North of Azores, East of Greenland)

Fishing mortality in relation to highest yield. Fishing mortality in relation to agreed target

SUMMARY OF ICES 2009 ADVICE FOR PELAGIC SPECIES incl Blue whiting, capelin, herring, Norway pout, sandeel and sprat

West Coast Rock Lobster. Description of sector. History of the fishery: Catch history

EU request to ICES on in-year advice on haddock (Melanogrammus aeglefinus) in Division 7.a (Irish Sea)

2017 NORTHERN COD STEWARDSHIP FISHERY MANAGEMENT PLAN PROPOSAL SUBMITTED TO

Paper prepared by the Secretariat

SCALLOP FISHERY AREA/TIME CLOSURE TO PROTECT COD SPAWNING AGGREGATIONS IN 5Z (GEORGES BANK)

A Combined Recruitment Index for Demersal Juvenile Cod in NAFO Divisions 3K and 3L

COUNTRIES THAT CONTRAVENE SCIENTIFIC ADVICE BY HARVESTING MIXED-POPULATIONS OF NORTH AMERICAN SALMON

5. purse seines 3 000

Herring (Clupea harengus) in subdivisions 20 24, spring spawners (Skagerrak, Kattegat, and western Baltic)

NEWFOUNDLAND AND LABRADOR REGION GROUNDFISH STOCK UPDATES

6.3.8 Advice May 2014 Version 2, ECOREGION North Sea STOCK Herring in Division IIIa and Subdivisions (western Baltic spring spawners)

Transcription:

Pêches et Océans Canada Sciences Fisheries and Oceans Canada Science DFO Sciences Stock Status Report B4-1 (1999) 52 6 59 58 57 51 QUEBEC LOWER NORTH SHORE 2 Meters 4Ra STRAIT OF BELLE ISLE ST. JOHN'S BAY NEW FEROLLE POINT RICHE 4Rb West Coast of Newfoundland Atlantic Herring Background Herring (Clupea harengus) are found throughout the waters of the northwest Atlantic from Labrador to Cape Hatteras. In Canada, they are fished mainly in southwestern Nova Scotia and the Bay of Fundy, within the Gulf of St. Lawrence, and in eastern and southern Newfoundland. Both spring- and autumnspawning herring are found along the west coast of Newfoundland (4R). Each seasonal-spawning population is considered to be a separate stock for fisheries management. The herring is a migratory species which over the course of a year, will travel extensively throughout its area of distribution from traditional nearshore spawning grounds, to feeding and overwintering areas, repeating these patterns year after year with considerable regularity. The major spring-spawning areas in 4R are located at the southern end of the coast in and around St. George's Bay (4Rd) and Portau-Port Bay (4Rc) although several other spawning sites are known along the coast towards the north in St. John Bay. Mature herring arrive and congregate in these areas from the end of April to the middle of June. Autumn spawning is concentrated mainly north of Point Riche (4Ra) from mid-july to mid- September. At other times of the year, these two spawning stocks are mostly found in mixed schools in either feeding or overwintering areas. The major feeding areas (off St. George's Bay in the spring, off Point Riche and in the Strait of Belle Isle in the summer, and in and around the major bays in the fall) are associated with concentrations of copepods (red-feed) and/or euphausiids (krill) which are their main food items. They are believed to overwinter in the deeper waters of the Esquiman Channel. 5 49 48 BEAUGE BANK 4Rd 4Rc ESQUIMAN CHANNEL CAPE ST. GEORGE ST. GEORGE'S BAY 3Pn PORT AU PORT BAY CAPE ANGUILLE BAY OF BONNE BAY ISLANDS CAPE ST GREGORY ST. PAUL'S INLET NEWFOUNDLAND Figure 1. Western Newfoundland (NAFO Division 4R) unit areas. Summary The 1999 assessment indicates that the status of the spring-spawning stock is in danger of collapse while the autumn spawning stock is declining gradually while the exploitation rate has been slowly increasing. Apart from the 199 yearclass, recruitment to the spring-spawning stock has been below average since the 1987 yearclass. The spring-spawner spawning-stock biomass (SSB) has declined to an historical low of 14, t in 1999. If the spring-spawner F.1 catch of 2,3 t is caught in 1999, there would be a 4% risk that the SSB would increase by 2% by the year 2, although the minimum SSB target of 38, cannot be achieved even without fishing. Recruitment to the autumn-spawning stock has been above average since the large 1979 yearclass, which has kept this stock at an intermediate level. March 1999

The autumn-spawner SSB has been declining slowly, from 8, t in 1984 to 42, t in 1998. An autumn-spawner F.1 yield for 1999 would be approximately 9, t and would result in a 9% risk that the spawning-stock biomass will decrease by 1%, although there is a 7% probability that the SSB will not decline below 35, t. It is essential that fishing effort be reduced and be shifted to the north as much as possible to avoid directed fishing on the spring-spawning stock. The fishery The herring stocks in 4R are exploited both in mixed schools and singularly in spawning aggregations from April to December mainly by large (>75') purse seiners, small (<65') purse seiners and to a lesser extent by fixed gillnetters. Since 1985, the proportion of the total catch taken by all purse seines has been in excess of 8%, and even reached 98% in 1993. Since 1986, total herring landings from the west coast of Newfoundland averaged 17,3 t (from 12,4 t to 26,4 t) as compared to an average of 14,1 t for the previous decade (Figure 2). LANDINGS (T) 4 35 3 25 2 15 1 5 ADVICE TAC 4Ra 4Rc 4Rd Figure 2. Cumulative commercial herring landings (t) by unit area from 1966 to 1998. (TAC and assessment advice are indicated). From 1984 to 1987, up to 8% of the purse seine catches were taken from October to December on over-wintering concentrations of herring in areas 4Rb and 4Rc. In 1988, the development of an over-the-side market to Russian vessels contributed to a considerable increase in landings in the spring fishery from 4Rc and 4Rd, from approximately 2, t in 1987 to 12,4 t in 1991. This spring purse-seine fishery accounted for over 7% of the total catch in 199 and 1993. This proportion has diminished to below 4% since 1994 when St. George s and Port-au-Port Bays were closed to commercial fishing during the spawning season. Between 1997 and 1998, there was a general displacement of the purse seine fleet towards the north. After an 4Rb 66 68 7 72 74 76 78 8 82 84 86 88 9 92 94 96 98 West coast of Newfoundland herring landings (t) by gear sector since 1988. Year Gear 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 **1998 Large purse seine 16353 1666 1631 25594 1277 1139 17634 1814 9473 7751 9468 Small purse seine 439 3752 3854 3392 372 353 3859 Gillnet* 1792 127 983 842 669 247 893 186 2279 2156 283 Total 18145 17687 17284 26437 15336 1538 1238 1612 14824 1296 16123 * includes bar seine and cod trap ** Preliminary statistics - 2 -

initial concentration in the southern bays in May of 1998, fishing activity was centered around Bonne Bay for the rest of the year. There was also an increase in activity in 4Ra in August, entirely on autumn spawners. It would appear from this displacement that herring densities were higher in the north than in the south. There has also been an increase in the activity of the smaller purse seiners along the west coast since 1989 where annual landings, which previously had not exceeded 8 t, reached 4,4 t in 1992. From 1993 to 1998, this fleet has landed from 3,1 t to 3,9 t annually. Due to a limited market demand for gillnetted herring, reported landings from fixed gear have generally been below 1% of the total 4R landings since 1985. A market has recently developed in 4Ra which has resulted in a steady increase in total gillnet landings from 8 t in 1994 to 2,8 t in 1998. Resource status Biological Indicators Historically, spring spawners have been dominant in the catch, averaging 72% of the catch in numbers, although this percentage has decreased to less than 5% in the last 4 years. This is due mainly to a decrease in the concentration of fishing on the spring spawning stock, as well as by a decrease in the spring-spawning stock itself, relative to the autumn spawners. In the late-fall purseseine fishery, there has been a trend of decreasing percentage spring spawners, from 75% in 1987 to 45% at present. Since the mid-198's, only the 198, 1982, 1987 and 199 spring-spawner yearclasses have been important contributors to the total catch. The 199 yearclass appeared for the first time in the gillnet catches inside of St. George's Bay and Port-au-Port Bay in the spring of 1996. In late 1998, the 1994 cohort was the dominant yearclass in the purse seine catches. Since 1983, the 1979, 1986, 1988 and 199 autumn-spawning yearclasses have been the most important contributors to the fishery for this stock. The 1979 yearclass was still dominant in 4Ra in 1997. WEIGHT (kg).35.3.25.2.15.1.5 AGE 4 AGE 6. 196 1965 197 1975 198 1985 199 1995 2 Figure 3. Mean weight at age 4 and 6 for spring-spawning herring in late fall (Oct-Dec) from 1964 to 1998. WEIGHT (kg).45.4.35.3.25.2.15 Age 4.1 Age 6.5. 196 1965 197 1975 198 1985 199 1995 2 Figure 4. Mean weight at age 4 and 6 for autumn-spawning herring in late fall (Oct-Dec) from 1964 to 1998. There has been a more or less constant decline in the weight at age of both spring and autumn spawners since the early 198s (Figure 3 and 4). The overall condition (weight vs. length) of west coast of Newfoundland herring showed a major decrease in 1993 and 1994 (Figure 5), corresponding with a general decrease in annual water temperatures noted for the northern Gulf of St. Lawrence. However, when put into the context of the last 28-3 -

years, average condition was much lower from 1973 to 1976. In 1995, overall condition rebounded to the high values seen throughout the 198 s, but has declined steadily since, indicating a return to poor feeding conditions. CONDITION FACTOR 82 8 78 76 74 72 7 68 66 AUTUMN SPRING 64 7 72 74 76 78 8 82 84 86 88 9 92 94 96 98 Figure 5. Condition factor for spring- and autumn-spawning herring in late fall (Oct-Dec) from 197 to 1998. Four species of seals: grey seals (Halichœrus grypus), harbour seals (Phoca vitulina), harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata) occur in the northern Gulf of St. Lawrence. Harp seals and grey seals are the most important seal predators owing to their abundance (harp seals), or time of residency in this area and possibly high incidence of herring in the diet (grey seals). Pinniped consumption of herring in 4R has most likely increased over the past decade with the growth of the harp seal population. Annual consumption was estimated to have now reached in the order of tens of thousands of tons, and is most likely concentrated on young herring. These estimates should be considered as very tentative, as many uncertainties are involved in the calculations. The scarcity of comprehensive diet information for pinnipeds in the northern Gulf, as well as their resident times are two of the major factors limiting attempts to quantify fish consumption in this area. However, the true impact of predation on 4R herring stocks cannot be evaluated until predation is considered within the context of total natural mortality. Abundance indicators Comments collected from written questionnaires sent to all licensed inshore herring fishermen in 4R as well as comments collected from index-fisherman logbooks indicated some improvement in the abundance of spring spawners around Port-au-Port Bay, St. George s Bay and Bay of Islands in 1996 relative to 1995, although it was felt that spawning activity had not yet improved significantly. The 199 springspawner yearclass, which had been captured in the fall purse seine fishery since 1994, had started to spawn in these southern bays. These observations are consistent with the catch rate data from index-fishermen in these areas. However, comments were generally negative in 1997 and 1998, indicating that the improvement was short lived, and there was a widespread opinion that the herring was small. Index fishermen logbooks stated that herring were scarce, schools were small and catches were the lowest seen for many years. North of Point Riche in 4Ra, the general opinion was that herring abundance was average to good in 1995 and 1996 especially in the summer and fall, although along the Labrador coast of the Strait of Belle Isle, comments indicated that the stock was in decline. Opinions were increasingly pessimistic in 1997 and 1998, although spawning was noted throughout St. John and St. Margaret Bays, around Ferolle Point. Fishermen noted that the herring showed a mixture of large and small sizes. - 4 -

Latitude (N) 51 5 49 48 Lourdes Heatherton S t. Georges Cow Head Rocky Harbour Port au Choix Daniel's Harbour 59. 58. 57. Longitude (W) Ferolle Point stock in good shape sto ck in declin e good spawning spawning in decline spawning grounds Figure 6. Distribution of inshore fishermen s opinions concerning the state of the herring stocks and spawning in 1998 from written questionnaires. The standardized spring-spawner gillnet catch rates from index fishermen indicated a systematic decline since 1987. This catch-rate index increased slightly in 1991 and 1997, with the recruitment of the 1987 and 199 yearclasses to this fishery, although neither yearclass was sufficiently abundant in the southern bays to reverse the declining trend. This index reached an historical low in 1998. CATCH RATE (kg/net/day: Standardized) 3. 2.5 2. 1.5 1..5 Quebec Bay of Islands S t. David Point Riche Newfoundland. 1985 1987 1989 1991 1993 1995 1997 1999 Figure 7. Standardized catch rates for springspawning herring from index-fisherman logbooks between 1985 and 1998. The autumn-spawning index-fisherman catch-rate index seemed to reflect the strong recruitment of the 1986 yearclass and was well above the 1-year average. Its subsequent sharp decline in 1992 and 1993 was unexpected given the low fishing effort on this stock. In addition, the recent recruitment of the 1988 and 199 yearclasses has not been reflected in the index, which puts in doubt its usefulness as a measure of abundance. This indexfisherman catch-rate series has become less reliable due to (1) a decrease in participation in the program (two to four logbooks annually since 1993) and (2) the decrease in availability to inshore gillnets as the herring have moved farther offshore. CATCH RATE (kg/net/day: Standardized) 3. 2.5 2. 1.5 1..5. 1984 1986 1988 199 1992 1994 1996 1998 Figure 8. Standardized catch rates for autumnspawning herring from index-fisherman logbooks between 1984 and 1997. Fall acoustic surveys have been conducted on a biennial basis since 1989 with the last survey in 1997. The 1995 and 1997 surveys were undertaken in close collaboration with the west coast large seiner fleet. This survey included the entire west coast of Newfoundland from St. George s Bay to the Strait of Belle Isle which adequately covered the stock area. The 1997 total spawning-stock biomass estimate of 67, t (19,5 t of spring spawners and 47,5 t of autumn spawners) was a decrease over the 1995 estimate of 86, t (38, t of spring spawners and - 5 -

48, t of autumn spawners)(figure 9). In 1995, 64% of the herring biomass surveyed was in the two most northerly strata, while in 1997, 8% was in the most northerly stratum. The last 4 surveys have shown a constant decline in the spring-spawners spawning biomass, while the autumn spawners appeared to be stable over the last three surveys. Figure 9. Biomass estimates of spring- and autumn-spawning herring from 1991 to 1997 from the biennial acoustic survey. The stock status assessment was based on a sequential population analysis (SPA) for the spring-spawning stock using the commercial catch at age, and abundance trends from both the index-fisherman catch rates (1985 to 1998) and the last 4 biennial acoustic surveys (1991 to 1997). This analysis revealed that the 5+ fishing mortality has risen more or less steadily on this stock since 1987 (Figure 1). Although the fishing mortality had remained around the F.1 target level of.3 in recent years, it rose sharply to.45 in 1998, mainly due to the concentration of fishing on spring spawners in the southern bays in the spring. BIOMASS (t) 18 16 14 12 1 8 6 4 2 Autumn Spawners Spring Spawners 1991 1992 1993 1994 1995 1996 1997 1998 5+ FISHING MORTALITY.5.45.4.35.3.25.2.15.1.5. F.1 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 Figure 1. Annual instantaneous fishing mortality (5+) for spring-spawning herring from 1965 to 1998. NUMBERS (') 9 8 7 6 5 4 3 2 1 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 CLASS Figure 11. Estimates of recruitment at age 2 for spring-spawning herring for yearclasses 1963 to 1994. Lines represent mean recruitment at low, medium and high levels. (yearclasses 1995 to 1997 are fixed at low and medium recruitment). This analysis showed that, apart from the 199 yearclass, recruitment has been below average since the 1987 yearclass (Figure 11). Even the 1994 yearclass, which was a significant portion of the 1998 catch at age, appears to be below average. The spawning-stock biomass has therefore declined to an historical low of 14, t in 1999 (Figure 12). If 2% of the virgin stock size is considered as the biological reference point for a stock in danger of collapse as suggested by the FFRC, that level would be 38, t for this stock. This assumes that the virgin stock size is equal to the maximum observed SSB, which was 19, in 1973. - 6 -

BIOMASS (t) 2 18 16 14 12 1 8 6 4 2 1964 1966 1968 197 1972 1974 1976 1978 198 1982 1984 1986 1988 199 1992 1994 1996 1998 2 SSB Catch Biomass Figure 12. Spawning-stock biomass and catch biomass for spring-spawning herring from 1965 to 1999. Because of the uncertainties with the indexfisherman catch rate, the autumn-spawner sequential population analysis used only the acoustic survey abundance index. As this index was last estimated in 1997 and is still a short time series, the autumn-spawning population was estimated only up to 1998 and was less certain than the spring-spawner analysis. The analysis indicated that the 6+ fishing mortality had risen slowly since 1985 but was still below the F.1 target of.3 (Figure 13). 6+ FISHING MORTALITY.35.3.25.2.15.1.5. 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 Figure 13. Annual instantaneous fishing mortality (6+) for autumn-spawning herring from 1965 to 1997. The spawning-stock biomass has been declining slowly since 1984, and was estimated to be 42, t in 1998 (Figure 14). The population estimates showed a well balanced age structure with an aboveaverage 1994 yearclass dominating the 1998 population. Recruitment has been above F.1 average since the large 1979 yearclass which has kept this stock at an intermediate level (Figure 15). BIOMASS (t) 1 9 8 7 6 5 4 3 2 1 1972 1974 1976 1978 198 1982 1984 1986 1988 199 1992 1994 1996 1998 SSB Catch Biomass Figure 14. Spawning-stock biomass and catch biomass for autumn-spawning herring from 1973 to 1998. NUMBERS (') 4 35 3 25 2 15 1 5 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 CLASS Figure 15. Estimates of recruitment at age 2 for autumn-spawning herring for yearclasses 1975 to 1994. Lines represent mean recruitment at low, medium and high levels. (yearclasses 1995 to 1996 are fixed at medium recruitment). Results from these assessments indicated that the spring-spawner analysis does not suffer from a retrospective pattern (a discrepancy between past assessments of stock status and current estimates using additional data). The acoustic time series was too short to conduct a retrospective analysis for the autumn-spawner stock. Outlook A calculated F.1 yield for the springspawner stock in 1999 would be approximately 2,3 t. However, uncertainty about yearclass abundance creates uncertainty in forecasted yields. This - 7 -

uncertainty is expressed as the risk of not achieving various reference targets. For example, a 1999 catch of 6,5 t (the 1998 spring-spawner catch) would result in a 1% risk of a further decrease in the spawning-stock biomass (Figure 16). A catch of 2,3 t would result in a 4% risk that even a 2% increase in mature biomass would not be achieved by the year 2 (from 14, t to 17, t). The minimum SSB target of 38, cannot be achieved in 2 even without fishing. A catch of 2,3 t therefore cannot be recommended if the primary objective is to rebuild this stock. flatness of the probability curve indicates that there is much uncertainty around this value (Figure 17). With this yield, there is a 9% risk that the spawning-stock biomass will decrease by at least 1%, but a 7% risk that the SSB will not decline below 35, t (the lowest observed value since 1973). Additional uncertainty arises because these projections are two years into the future (from 1998 to 2) and because medium recruitment at age 2 is assumed for 1997 through to 2. 1..9 PROBABILITY 1..9.8.7.6.5.4.3.2.1. F.1 1998 CATCH F>.3 SSB 2 < 38 t SSB 2 < SSB 1999 SSB 2 < SSB 1999 + 2% 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1999 QUOTA (t) Figure 16. Risk analysis for spring-spawning herring with the probability of not reaching various objectives given various quotas in 1999 assuming medium recruitment. These uncertainty calculations do not include variations in catch at age, partial recruitment to the fishery, natural mortality or future recruitment. In particular, because the recruitment of age 2 fish in 1998, 1999 and 2 is unknown, medium recruitment was assumed for the projections. If however, the recruitment of these yearclasses is low, as has been observed since the 199 yearclass, the calculated F.1 yield in 1999 would be around 1,2 t, and would result in a 7% risk of the SSB not increasing by even 1%. A calculated F.1 yield in 1999 for the autumn-spawning stock would be approximately 9, t (close to the 1998 autumn-spawner catch), although the PROBABILITY.8.7.6.5.4.3.2.1 Prob. F >.3 SSB 2 < 35 SSB 2 < SSB 1999 SSB 2 < SSB 1999-1%. 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11, 1999 QUOTA (t) Figure 17. Risk analysis for autumn-spawning herring with the probability of not reaching various objectives given various quotas in 1999 assuming medium recruitment. Management considerations The 1999 assessment of western Newfoundland herring indicates that in general, fishing mortality on these stocks has been increasing over the past 12-15 years and had been around F.1 for the spring spawners between 1991 and 1997. The closure of St. George's Bay and Port-au-Port Bay in 1995 had the desired affect of slowing the decline of this stock by concentrating fishing on the autumn spawners, of decreasing the quantity of spring spawners in the total catch and of allowing these fish to spawn undisturbed. However, the present analyses show that the resumption of fishing in these southern bays in 1998 was premature, and that the concentrated harvesting of spring spawners F.1 1998 CATCH - 8 -

in the spring fishery resulted in a sharp increase in fishing mortality. Comments received from index fishermen and questionnaires suggested that there was some improvement in abundance in 1996 in St. George s Bay and Port-au-Port Bay. The 199 yearclass caused an increase in the spring-spawner gillnet catch rates between 1996 and 1997 when it recruited to this fishery. However, both the index-fisherman catch rates and the majority of the questionnaire comments have subsequently indicated that the increase was short-lived, and that the stock has continued to decline since 1997 and has now reached an historical low. It is projected that the 1994 yearclass will not be sufficient to bolster the spring-spawning stock. The present analyses have shown that recruitment to the spring-spawning stock has been consistently below average since the 199 yearclass, which was the last of any significance. Throughout the past 3 years, this stock has been supported by exceptionally large yearclasses which appear on roughly a 1-12 year cycle. As over 15 years have passed since the last large recruitment pulse (198 and 1982 yearclasses), the production of this stock (growth and recruitment) has not kept up with removals (catches and natural mortality). In addition, the pattern of recruitment against spawning-stock biomass indicates that the chances of this stock producing a strong yearclass decreases sharply below about 5, t (Bbuf) (Figure 18). Although the estimates are subject to large uncertainties, increased consumption of herring by seals may have helped to reduce the productivity of this stock over the past decade. RECRUITMENT AT AGE 2 (') 9 8 7 6 5 4 3 2 1 1999 SSB BLIM 1965 BBUF 1994 25 5 75 1 125 15 175 2 SSB (t) Figure 18. Stock-recruitment relationship, minimum spawning-stock biomass (Blim) and buffer spawning-stock biomass (Bbuf) for spring-spawning herring from 1965 to 1994. The autumn-spawning stock has historically received less fishing effort and has constituted less of the total catch (<28%) than the spring spawners because it is distributed more in the northern areas farther from the principle landing ports. This has resulted in a wider age distribution in this stock, with the 199 yearclass appearing as very strong and the 1994 yearclass as above average. Although the autumn-spawners are at an intermediate stock size, they are declining slowly and will not be able to support the present TAC of 22, t, nor recent catch levels (between 12, and 16, t). Fishing of 4R herring will therefore have to be reduced to a sustainable level. Precautionary principles suggest that this would be no more that 9, t for the autumn-spawners and that no directed fishery be prosecuted on concentrations of spring spawners. It is recommended that a harvest limit be imposed for the southern end of 4R. To avoid a repetition of intensive fishing on any other component, either spring- or autumn-spawning, it is recommended that fishing effort be reduced and spreadout along the remainder of the coast and throughout the year as much as possible. The continuation and enhancement of the index-fisherman program in St. George's Bay and Port-au-Port Bay is - 9 -

essential for the close monitoring of spawning activity in this area and as a spring-spawner abundance index. The present analyses indicate that the spring-spawning stock has declined to a point where fishing must be curtailed to avoid a collapse. This dangerous reduction in the SSB has occurred even though the average fishing mortality has been around the F.1 target of.3 since 1991. The autumn-spawning stock has been declining gradually while the exploitation rate has been increasing since the mid-198 s. These divergent trends have occurred despite above-average recruitment over the past 15 years and a fishing mortality well below the F.1 target. This suggests that the target exploitation rate may be too high for these stocks and should be re-evaluated. Finally, an analysis was conducted at the request of Industry to re-examine the minimum size limit of 26.5 cm fork length imposed on 4R herring catches. The main reason for this regulation was to protect juvenile fish and to allow maturing herring to spawn undisturbed at least once before recruiting to the fishery. The analysis evaluated the percent maturity at length for each stock and concluded that on average, 8% of spring- and autumn-spawners are mature at 25. and 25.5 cm fork length, respectively. Although this suggests a lowering of the minimum size limit to 25.5 cm may be justified, the present low springspawner stock size would argue against an increase in the targeting of young fish at this time. For more information: McQuinn, I.H. and L. Lefebvre. 1999. An Assessment and Risk Projections of the West Coast of Newfoundland (NAFO Division 4R) Herring Stocks (1965 to 2). DFO Atlantic Fisheries Res. Doc. 99/--. McQuinn, I.H. and L. Lefebvre. 1999. An Evaluation of the Western Newfoundland Herring Acoustic Abundance Index from 1989 to 1997. DFO Atlantic Fisheries Res. Doc. 99/--. Prepared by: Ian McQuinn Tél. (418)775-627 Fax. (418)775-74 Email: mcquinni@dfo-mpo.gc.ca Correct citation for this publication DFO, 1999. West Coast of Newfoundland Atlantic Herring. DFO Science Stock Status Report B4-1 (1999).! "# $ %&' ()* +,!- ++. */*( 1! # # #2! " Pêches et Océans Canada Sciences Fisheries and Oceans Canada Science - 1 -