Benchmark Workshop for Harp and Hooded Seals (WKBSEALS)

The benchmark was tasked with evaluating proposed developments to the assessment model used for two stocks of harp seals (East Ice [White Sea/Barents Sea, seh.27.1] and West Ice [Greenland, seh.27.125a14]) and one stock of hooded seals (West Ice [Greenland, sez.27.2514]) in the Northeast Atlantic. The benchmark concluded that there were sufficient data to produce an assessment model for the West Ice (Greenland Sea) stock of harp seals but that data were insufficient for the East Ice (Barents Sea / White Sea) harp seal stock and too weak a signal for the West Ice hooded seals for viable assessments for these stocks.

There has been no pup production survey for East Ice harp seals since 2013. In the absence of more recent survey data, the benchmark concludes that viable assessment of current stock status or catch advice cannot be produced. Furthermore, the most recent available pup production estimates indicated a poor status. There have been limited catches since 2019, and the benchmark recommends that a pup survey and subsequent revised assessment is required prior to the resumption of any substantial commercial hunt. The model version with capelin abundance informing model dynamics does perform well in the time period for which data exist.

For the West Ice harp seal stock, the benchmark proposes a revised assessment model using cod and capelin alongside a first order autocorrelation (AR1) process to drive the model dynamics. Owing to the provisional nature of the recent pup survey, Reference Points are not calculated here but will be evaluated at WGHARP 2023 when the final data is available. The historical modelled population absolute level is uncertain, but the overall recent trend is relatively flat and has not been adversely affected by recent catches. Although a harvest is taken, advice is not currently given through ICES. An existing HCR is used (see section 6.3., ICES, 2005) for advice outside ICES, and there is a desire to conduct an HCR evaluation to produce a basis for future ICES advice.

The benchmark notes the current low level of the hooded seal stock and that no commercial hunting has been conducted since 2007. No commercial hunting should be considered unless a clear upward trend in the pup abundance estimate can be observed, taking account of the uncertainty in these data. In the event of such an improving trend being observed, a new revised assessment would be needed prior to the resumption of hunting in order to give information on stock status and potential harvest levels.

The benchmark also performed a preliminary evaluation of the existing catch-at-age data for the different stocks. There was sufficient sign of signal in the data consistent with population structure (exponential decay with age, sign of recruitment failure tracking between years) to consider the possibility for using these data for model tuning. The benchmark strongly encourages such work.