Biological State and Trend
|Figure 188.8.131.52 |
The assessment is considered indicative of stock trends, and provides relative measures of stock status rather than absolute. Throughout the history of the fishery, estimates of stock biomass have been above Btrigger
and fishing mortality below FMSY
. The estimated risk of falling below Btrigger
or of exceeding FMSY
by the end of 2012 is less than 1%. Recruitment indices showed no major changes in the period 2004–2012.
Habitat and Biology
Depth zone: Shelf (50 m - 200 m). Vertical distribution: Demersal/Benthic.
Northern shrimp are hermaphroditic. Individuals start out as males, but after 3–4 years they change sex and complete their lives as females. Various fish and marine mammal species prey on Northern shrimp, and predation is considered important in influencing Northern shrimp stock dynamics.
Jurisdictional distribution: Shared between nations
Considered a single stock: Yes
Norwegian and Russian vessels exploit the stock over the entire resource area, while vessels from other nations are restricted to the Svalbard fishery zone. No overall TAC has been established for this stock, and the fishery is partly regulated by effort control, licensing, and a partial TAC (Russian zone only). Bycatch is constrained by mandatory sorting grids and by temporary closures of areas where high bycatch occurs of juvenile cod, haddock, Greenland halibut, redfish, or small shrimp (<15 mm). The minimum mesh size is 35 mm.
Effects of the fisheries on the ecosystem
|Catch by fleet ||Total catch (2011) = 29.790 kt, where 100% are landings (100% trawl). |
Small-mesh trawls are used to catch Northern shrimp, frequently with a bycatch of juvenile fish. However, overall bycatch is considered to be relatively small due to the use of mandatory sorting grids and temporary closures of areas where high bycatch occurs.
ICES advises that catches of 60 000 tonnes in 2013 will maintain the stock at the current high biomass.
Overall Assessment Results
|Figure 184.108.40.206 Northern shrimp in Subareas I and II (Barents Sea). Summary of stock assessment. Catches 2012 projected to the end of the year. Recruitment index: abundance of Northern shrimp at size 13–16 mm CL from Norwegian (2004–2008) and Russian (2006–2012) surveys. Below: Median estimates of the relative biomass (B/BMSY) and fishing mortality (F/FMSY): Grey boxes are inter-quartile ranges; the arms of each box are the 95% credibility interval of the distribution. Top right: Fishable biomass and F over the years. |
Assessment ModelQuality consideration
The assessment model best describes trends in stock development and is not fully sensitive to year-to-year changes. Large and rapid changes in recruitment may therefore not be fully captured in model predictions. If predation on Northern shrimp were to increase rapidly outside the range in the modelled period (1970–2012), the stock size might change more than the modelling results indicate.Scientific basis
|Assessment type ||Bayesian version of a surplus-production model. |
|Input data ||Three survey indices (the Norwegian shrimp survey 1982–2004, the Russian shrimp survey 1984–2005, and the Norwegian–Russian ecosystem survey Eco-Norw-Q3 since 2004); one commercial index (standardized cpue since 1970). |
|Discards and bycatch ||Not included in the assessment. |
|Indicators ||None. |
|Other information ||Bayesian stock–production model introduced in 2006. |
|Working group report ||NIPAG |
Management unit: YesManagement plans
No specific management objectives are known to ICES.
Source of information
The above excerpts are from the first two pages of the ICES advice, the supporting information to this advice can be read in full at the following reference:
ICES. Northern shrimp (Pandalus borealis) in Subareas I and II (Barents Sea). Report of the ICES Advisory Committee, 2012. ICES Advice, November 2012. http://www.ices.dk/committe/acom/comwork/report/2012/2012/pand-barn.pdf