The CFRA: A Joint Assessment of South China Sea Skipjack Tuna Stocks Authors:

Size selectivity: A critical assumption of the original formulation of LBSPR assessment used here is that the size composition data analysed are representative of the size composition of the adults of the 10 stock being assessed. [...] Nevertheless, the estimates of the size selectivity of the smaller fish in the catch derived from the analysis of catches caught with dome-shaped selectivity can still inform our broader ‘weight of evidence’ diagnosis of the SCS fisheries for SKJ. [...] These observations raise the issue as to the extent to which we are over-estimating the SPR of the SCS SKJ resource, and whether the survival of juvenile SKJ is sufficient to sustain the adult portion of stocks. [...] With the purse seine fishery (figure 4) the size of selectivity is smaller than the size of maturity (SL50 < Lm), while with the gillnet fishery (figure 5) the size of selectivity is similar to the size of maturity (SL50 ~ Lm). [...] Many facets of the SCS SKJ fishery are suggestive of these symptoms of overfishing: The Race for Fish and Fishing Down Food Web The evolution of the fishing gears used to catch SCS SKJ is suggestive of the race for fish and fishing down of the food web.