Certification of selective fisheries could be detrimental to some stocks

The Marine Stewardship Council certification of the PNA (Parties to the Nauru Agreement) unassociated-sets purse seine fishery, which targets free-swimming schools, can shift fishing pressure away from FADs. Moreover, certification might enable the PNA to negotiate a higher access fee from foreign vessels as consumers are willing to pay more for certified seafood. Yet, there are also risks. The ecolabel stimulates consumption of the certified product, and thus may increase the overall demand for tuna. At the same time, less sustainability-conscious consumers might switch to cheaper FAD-caught tuna. Moreover, unassociated purse seine sets catch relatively more adult yellowfin tuna than the FAD fishery, so certification could be detrimental to this stock.

Groeneveld and Quaas investigated these biological and economic effects in a quantiative bioeconomic model of  the WCPO tuna fishery. They find that the effect on skipjack and bigeye tuna stocks is likely to be positive, but the effects on adult yellowfin tuna stocks and the PNA access fee depend strongly on the certified fishery's catch rate of adult yellowfin tuna. If unassociated-sets purse seine fishers keep catching adult yellowfin tuna at the same rate as now, certification might actually reduce adult yellowfin stocks and the access fee . If both the FAD and the unassociated-sets fishery would have the same catch rate of adult yellowfin tuna, however, certification enhances all age classes of yellowfin and bigeye tuna, and increases the access fee. These findings suggest that certification of more selective fisheries is not enough to protect all stocks, but it should be accompanied by measures targeted at specific stocks.