Norway lobster (Nephrops spp.) in Division IIIa (Skagerrak and Kattegat)

Transcription

1 ICES Advice on fishing opportunities, catch, and effort Greater North Sea Ecoregion Published 30 June Norway lobster (Nephrops spp.) in Division IIIa (Skagerrak and Kattegat) ICES stock advice ICES advises that when the MSY approach is applied catches in 2016 (assuming a landing obligation applies) should be no more than tonnes. If this stock is not under the EU landing obligation in 2016 and discard rates do not change from the average ( ), this implies landings of no more than 7827 tonnes. Stock development over time Stock size is considered to be stable. The estimated harvest ratios suggest that the fishing mortality (F) for this stock is currently below FMSY. Figure Norway lobster in Division IIIa. Long-term trends in landings ( ) and catches ( ), harvest rate (red dashed line = F MSY harvest rate), and UWTV abundance (used as F and SSB proxies. Weights in tonnes, UWTV in millions). Stock and exploitation status Table Maximum Sustainable Yield Precautionary approach Management Plan Norway lobster in Division IIIa. State of the stock and fishery, relative to reference points. Fishing pressure Stock size F MSY Appropriate MSY B trigger Undefined F pa, F lim Below possible reference points B pa, B lim Undefined F MGT Not applicable SSB MGT Not applicable ICES Advice 2015, Book 6 1

2 Published 30 June 2015 Advice on fishing opportunities, catch, and effort Catch options Table Norway lobster in Division IIIa. The basis for the catch options. Variable Value Source Notes Abundance in TV assessment 3762 million ICES 2015a UWTV 2014 Mean weight in landings 59.4g ICES 2015a Average Mean weight in discards 27.9g ICES 2015a average Discard proportion 62.6% ICES 2015a average (proportion by number) Discard survival rate 25% ICES 2015a average (proportion by number) , Only applies in scenarios where discarding allowed Dead discard rate 55.66% ICES 2015a average (proportion by number), Only applies in scenarios where discarding allowed Table Norway lobster in Division IIIa. The catch options. All weights in tonnes. Landing obligation Basis Total catch Wanted catch* Unwanted catch** Harvest rate** MSY approach % F current ( ) % * Wanted and unwanted catch are used to described Nephrops that would be landed and discarded in the absence of the EU landing obligation based on discard rates estimates for average ( ). ** calculated for dead removals and applied to total catch. Discarding allowed Basis Total catch Dead removals Landings Dead discards Surviving discards Harvest rate * L+DD+SD L+DD L DD SD for L+DD MSY approach % * calculated for dead removals Basis of the advice Table Norway lobster in Division IIIa. The basis of the advice. Advice basis MSY approach Management plan There is no management plan for Norway lobster in this area. Quality of the assessment The UWTV surveys in 2011 to 2014 were conducted in all six main fishing areas in Division IIIa. During 2014, the survey area was extended into the western Skagerrak. Creel fished Nephrops grounds in Division IIIa are not covered by the survey but would add to the abundance estimate. The abundance for the total ground is likely to be higher than currently estimated. Issues relevant for the advice The estimated burrow density in Division IIIa is medium ( burrows m 2 ) and the observed harvest ratio is between F0.1 and Fmax. Based on the ICES MSY approach for Nephrops this means that F35%SPR may be selected as a proxy for FMSY. F35%SPR is unusually higher than Fmax for this stock due to the very high discard proportions observed in the fishery. Therefore, Fmax is chosen as a conservative proxy for FMSY. A mismatch between mesh size in trawl fisheries and minimum landing size (carapace length 40 mm, which is higher than most North Sea FUs) results in a high discard proportion for this stock. The two functional units in Division IIIa, Skagerrak (FU 3) and Kattegat (FU 4), are considered to be a single stock. 2 ICES Advice 2015, Book 6

3 ICES Advice on fishing opportunities, catch, and effort Published 30 June Noup Fladen Norwegian Deep 58 Moray Firth Skagerrak latitude 56 Firth of Forth Devil's Hole Off Horn's Reef Kattegat Farn Deeps 54 Botney Gut longitude Figure Nephrops Functional Units in the North Sea and Skagerrak/Kattegat region. ICES Advice 2015, Book 6 3

4 Published 30 June 2015 Advice on fishing opportunities, catch, and effort Reference points Table Norway lobster in Division IIIa. Reference points, values and their technical basis. Framework Reference point Value Technical basis Source It is not possible to determine an appropriate MSY B trigger at this MSY B trigger MSY time because of the short survey series. ICES 2015a approach Harvest ratio F MSY= F max 7.9%. Equivalent to F max combined sex. ICES, 2011 B lim Precautionary B pa approach F lim F pa Management plan SSB MGT F MGT Basis of the assessment Table Norway lobster in Division IIIa. The basis of the assessment. ICES stock Data Category 1 (ICES, 2015b) Assessment type Underwater TV survey linked to yield-per-recruit analysis from length data (ICES 2015a). Input data Commercial catches (from logbook data). One survey index (UWTV), length frequency data, and discard samples. Annual maturity data from commercial catch samples. Natural mortalities from literature (Morizur, 1982). Discards and bycatch Included in the assessment, data series from the majority of the fleet/ main fleets (covering 100% of the landings in 2014) Indicators Landings per unit effort, mean size. Other information None. Working group Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK) 4 ICES Advice 2015, Book 6

5 ICES Advice on fishing opportunities, catch, and effort Published 30 June 2015 Information from stakeholders Results for Nephrops exist in the fishers survey for Area 8-9, which indicates that the abundance has increased in this area during the last decade (Napier 2014). Figure Cumulative time series of index of perceptions of abundance of Nephrops, by area (see page 14 for explanation of the index). From Napier (2014). ICES Advice 2015, Book 6 5

6 Published 30 June 2015 Advice on fishing opportunities, catch, and effort History of advice, catch and management Table Norway lobster in Division IIIa. History of ICES advice, the agreed TAC, and ICES estimates of landings. All weights in thousand tonnes. Year ICES advice Landings advice Catch advice Agreed TAC ICES landings ICES discards ~ ~ Status quo TAC Status quo TAC Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level No increase in effort No increase in effort No increase in effort Current effort appears to be sustainable < Current effort appears to be sustainable < Recent average landings ( ) < MSY approach < MSY approach < MSY approach < MSY approach < < MSY approach < * * Assumes the landing obligation comes into force and selection patterns do not change. 6 ICES Advice 2015, Book 6

7 ICES Advice on fishing opportunities, catch, and effort Published 30 June 2015 History of catch and landings Table Norway lobster in Division IIIa. Catch distribution by fleet in 2014 as estimated by ICES. Dead removals (2014) Landings 5.5 kt Discards 91% trawling 9% creels 1.39 kt dead discards in weight 4.15 kt Table Norway lobster in Division IIIa. History of commercial catch and landings, both official and ICES estimated values are presented by area for each country participating in the fishery. All weights in tonnes. Year Denmark Norway Sweden Germany Total landings Total disc. Total catch ICES Advice 2015, Book 6 7

8 Published 30 June 2015 Advice on fishing opportunities, catch, and effort Summary of the assessment Figure Mean sizes in landings (white) and discards (black) in Skagerrak and Kattegat. Figure Danish and Swedish combined effort and LPUE trends in IIIa 1990 to 2014 Table Norway lobster in Division IIIa. Assessment summary with weights (in tonnes). Year TV abundance index (millions) Landings (t) Discard rate (weight) Mean Weight Landings(g) Mean Weight Discards (g) N removed (millions) Observed Harvest Rate % % % % % % % % Sources and references ICES Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 5 11 May ICES CM 2010/ACOM:13. ICES Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 4 10 May 2011, ICES Headquarters, Copenhagen. ICES CM 2011/ACOM: pp ICES. 2015a. Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 28 April 7 May ICES CM 2015/ACOM:13. ICES. 2015b. Advice basis. In Report of the ICES Advisory Committee, ICES Advice 2015, Book 1, Section 1.2. In preparation. Napier, I. R Fishers North Sea stock survey NAFC Marine Centre, Shetland, Scotland. Morizur, Y Estimation de la mortalité pour quelque stocks de langoustine, Nephrops norvegicus. ICES CM 1982/K:10. 8 ICES Advice 2015, Book 6