Report of the Working Group on Biology and Assessment of Deep-sea Fisheries Resources (WGDEEP), 4–11 April 2014 Copenhagen, Denmark
|Ref.||ICES CM 2014/ACOM:17|
|Contributor(s)||Lorance Pascal, Pawlowski Lionel|
|Note||ICES WGDEEP REPORT 2014 ICES ADVISORY COMMITTEE|
|Abstract||WGDEEP met at ICES Headquarters in Copenhagen, Denmark on 4–11 April 2014. The group was chaired by Pascal Lorance from France and Gudmundur Thordarson from Iceland. Terms of Reference of the Working Group are given in Section 2.
2014 was the first year WGDEEP gives advice according to a new advice schedule. In short it means that for half of the stocks advice is given in year y and the other half has advice in year y+1. The exception from this schedule is stocks from Va (Iceland) that will have advice annually. Available time-series for international landings and discards, fishing effort, survey indices and biological information were updated and for all stocks and are presented in Sections 4 to 14 of the report.
For some fisheries, significant discrepancies were found between official landings data supplied to ICES and scientific estimates of landings. In order to maintain the consistency of time-series (which previously used only scientific estimates), some landings have been included in the data tables as “unallocated landing” (see Section 2.2).
The EG provided generic commentary on the application of the HCR to deep-water stocks in the ICES area and specific comments on the application of the HCR in the 2012 advisory process with respect to specific stocks assessed by WGDEEP. In particular, it was found that, when catches decrease year on year it may not be sensible to use a three year average as the basis in the 3.2 rule or other DLS rules that use catches.
This may result in higher advice, even with the 20% buffer and the additional 20% cap, than the catches in the terminal year. To further develop methods to provide quantitative advice consistent with the MSY framework, WGDEEP has applied a new approach to Productivity Susceptibility Analysis (PSA) using orange roughy stocks to the west of the British Isles as a case study (Chapter 15). Following WKDEEP 2014, a particular HCR was also adopted for black scabbardfish; assessed for the first time as a unique stock widespread in the NE Atlantic, which spatially and technically distinct fisheries exploit in Faroese waters, Celtic Seas, West Iberia and Azores.
Significant progress in the reliability of several assessments was achieved. The benchmark from WKDEEP 2014 applied to three stocks, ling in Va, blue ling in Vb, VI and VII and black scabbardfish in Vb, VI, VII, VIII and IX. The assessment of ling in VA using GADGET, developed as exploratory assessment in recent years, is now benchmark as a fully analytical model. The spawning stock of ling in Va is estimated to have reached in 2013 a highest observed level in 30 years, three times above the 1982–2002 average. The state of other ling stocks is diverse and overall less favourable.
Blue ling stocks also showed different status amongst stock units with strong variations in catch, recruitment and biomass in Va, a sustained increased in biomass in relation to a decrease fishing mortality in Vb, VI and VII, and a persistent low level in other areas.
Assessment of tusk was carried out as described in the stock annex, the main progress being made is the standardization of cpue series for many of the stock units and a new estimate of FMSY for tusk in Va. Estimates of biomass for tusk in Va from the GADGET model were revised downward the main reason being a significant drop in the tuning series in 2014 (Icelandic March survey).
Currently ICES advices on two stock units of greater silver smelt, in Va and other areas. WGDEEP-2014 proposes to split the other areas GSS into three advisory units; Area I and II, Vb and VIa and finally other areas. Exploratory assessments were presented for GSS in Va (GADGET) and Vb (XSA).
A new approach for orange roughy, where a Productivity Susceptibility Analysis (PSA), was used to appraising the likely impact of existing fisheries on stocks of this species. Previous perceptions that orange roughy stocks were depleted in the northeast Atlantic are not changed but the PSA suggests that the bycatch of orange roughy in current fisheries is sustainable for orange roughy stocks.
The status of the stocks of roundnose grenadier are varied. Roundnose grenadier in Vb, VI, VII and XIIb is assessed using a Bayesian surplus production model since 2010. The fishing pressure in 2013 is estimated low, the biomass is slowly rebuilding after two decades of over-exploitation. Roundnose grenadier in the Skagerrak was overexploited in the first half on the 2000s, the limited data available suggest it’s now at low level and may be rebuilding under a no catch regulation. The state of roundnose grenadier stocks on the Mid-Atlantic Ridge is unclear owing to very limited data. In this area there was significant fisheries in the past, past to the 1970s, the declined since the 1990s, but increased slightly if the last three years. In other areas, roundnose grenadier occurs at low level.
The assessment of black scabbardfish was benchmarked at WKDEEP 2014. This species was formerly assessed in three units in the ICES area. Although no final conclusion is reached all available evidence suggest that a single stock does a large clockwise migrations in the Northeast Atlantic and further south in the CECAF areas where spawning occurs. Whether fish in Azorean waters and on the Mid-Atlantic Ridge (ICES Subareas X and XII) belongs to the same widely distributed stock is uncertain and the picture in Subarea X is further blurred by the mixing with the closely related intermediate scabbardfish (Aphanopus intermedius).
Greater forkbeard is caught mostly as a bycatch. Adults are a landed bycatch in slope fisheries for hake, monkfish, megrims and deep-water species and juveniles are a discarded bycatch in numerous fisheries. The assessment is based upon indices from four surveys, which suggest increasing biomass in all areas.
Alfonsinos are a mixture of two species (Beryx splendens and Beryx decadactylus. These species are oceanic demersal species occurring at the top of seamounts and along slopes, where they form local aggregations. They are widespread in the Northeast Atlantic from Iceland to the Azores and along the continental slope, in particular to the west of Iberia and Bay of Biscay. The stock structure is uncertain and data very limited. Although a longline survey is carried out in the Azores, where most of the catch occur, the reliably of survey indices is uncertain for these species owing to their large and patchy spatial distributions. As a consequence, the perception of the status of these stocks relies primarily on catch trends.
A reliable estimate of the fishing effort of the Spanish artisanal fleet in the Strait of Gibraltar was used to calculate cpues and the results trend over the last five years confirmed the previous expert judgement that this stock was severely overexploited by artisanal fisheries. The use of the new fishery-dependent biomass index may need being scrutinized by the ICES benchmark process. The stock of the same species in the Azores (ICES Subarea X) also showed signs of overexploitation, while the third blackspot seabream stock in ICES Subareas VI, VII and VIII remains at a low level, since its collapse in the 1980s.
In response to a request from the NEAFC, the working group update descriptions of deep-water fisheries in the NEAFC and ICES areas by compiling data on catch/landings, fishing effort and known spawning areas and areas of local depletion at the finest spatial resolution possible by ICES subarea and division (Chapter 15).