Assessment of Cumberland Sound Greenland Halibut

Using catch composition data from the commercial fishery, data from the fishery independent survey, and recruitment parameter values from other Canadian Greenland Halibut stocks a generic Greenland Halibut population model was developed. Given the lack of local reproduction and the fact that population models attempt to replicate the dynamics of a population from recruitment through growth to maturity and reproduction, the validity of the population model was discussed. By consensus the model was not used to provide science advice. (Terms of Reference [ToR] objectives 1 and 2) In the absence of an accepted stock model the sustainability of specific TAH levels could not be assessed. (ToR objective 2) Fishery and survey data, along with local knowledge and Traditional Knowledge indicate the stock has been relatively stable since 2005. (ToR objective 1) Recent length-frequency, mean weight and growth (length-weight relationship) data from fishery-independent sampling and plant sampling programs are still broad in range when compared to historical information. Catch-per-unit-effort in the commercial fishery has been stable throughout most of the time series. Community fishers have experienced good catch rates in both shallow and deep water, from Kekerten Island to north of Pangnirtung Fiord, suggesting Greenland Halibut are still abundant in the stock area. The DFO Precautionary Approach framework typically uses reference points related to stock biomass to assess the current status of a stock. When biomass estimates are not available, abundance or biomass indices or population characteristics such as mean size or age structure can be used. For this fishery, the abundance index from the fishery-independent survey and the length-frequency in the commercial catch during 1997 to 2005 should be explored as potential interim reference points until data allow the development of biomass-based reference points. (ToR objective 1) Data from acoustic and floy tagging programs were presented that showed seasonal movement of tagged Greenland Halibut across the previous Cumberland Sound Turbot Management Area boundary near Kekerten Island. Given the consistency of the movement pattern among three years of tracking, there is no biological rationale to return the boundary to its original position. (ToR objective 3) Tagging data demonstrated movement of individual Greenland Halibut out of Cumberland Sound, counter to the previous assumption that Greenland Halibut enter Cumberland Sound but never leave and demonstrating connectivity with the offshore areas. (ToR objective 3) The potential of a carry-forward provision was discussed. It was suggested that the Department’s Quota Carry-Forward Guidelines for Atlantic Canada could apply, in which case up to 15% of the TAC could be carried forward. (ToR objective 4) Any harvest level increase or implementation of a carry-forward provision should be supported by a Traditional Knowledge and scientific monitoring plan. (ToR objectives 3 and 4)