engleski

Reply to Santojanni’s comments on "Is anchovy (Engraulis encrasicolus, L.) overfished in the Adriatic Sea?”, Ecol. Model. 201: 312–316

In his letter Santojanni (2008) provides important insights concerning anchovy stock assessment and fishery practice in the Adriatic Sea, while commenting the results of our model (Klanjšček and Legović, 2007). His major concern lies in our interpretation of the cause of the anchovy fisheries collapse in 1987. He states that due to uncertainty we should not have drawn such a clear cut conclusion based on our modeling results, as we apparently did. Our model is not in contradiction with regard to the threshold value of exploitation. Indeed, if we run a simulation with the expected recruitments and fishing mortality analogous to threshold value, the stock declines but not to the levels reported during the collapse. Similarly, the simulations with the exploitation rate of 0.5 show a greater decrease in stock size, but again not the collapse. The reason why mentioned simulations do not perceive the collapse, and the one performed in the paper does, lies in the fact that the collapse was simulated with the fishing mortality analogous to exploitation rate of 0.6. Santojanni et al. (2003) wrote: “Consequently, the exploitation rate, i.e. the ratio F/(F+M), is equal to 0.36 in the period 1975-1996, and in particular 0.60 in 1985.” The divergence in the interpretation of the fishing effort is in the different partitioning of the data in the time window ; a calendar year in Santojanni et al. (2003), and the split year in Santojanni et al. (2006b, 2008). Also, the data originate from the stock estimates that Santojanni (2008) refers to as precautionary series. Santojanni (2008) is objecting to the use of only these series, since they lower the stock estimates, while increasing the fishing effort. However, we believe that, even though these were the only series available to us, according to the precautionary principle, it is these series that should have been used for modeling.

engraulis encrasicolus ; overfishing ; Adriatic Sea

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