Dec 9 2014

NGO critics of California’s sardine rules miss that better science mean conservative management

Seafood NewsPublished with permission of SEAFOODNEWS.COM

By D. B. Pleschner [Opinion]  Dec 8, 2014

Recently the Pacific Fishery Management Council voted to change the sardine harvest control rule, increasing the upper limit of the sardine harvest fraction from 15 to 20 percent. The decision came after an exhaustive set of scientific workshops and analysis involving more than 60 people, held over the past two years to respond to a research paper that suggested that sea surface temperature (SST) measured at Scripps Pier in southern California, which had been employed as a proxy for sardine recruitment, was no longer correlated with recruitment success.

But apparently this fact was lost on environmental activists, who cried foul to the media, claiming that sardines are crashing, and the management response to the crisis is to just fish harder.

Claims that the Council voted for a more aggressive fishing rate miss the point: nothing could be further from the truth. But the truth is complicated.

We know that California’s sardine population is strongly influenced by ocean temperatures: warmer waters tend to increase sardine productivity, while colder waters tend to decrease it.

“The northern sardine stock has been declining for several years due to poor recruitment, and there is concern that it will decline further in the next couple of years, ” says Dr. Richard Parrish, one of the authors of the original sardine control rule. “Although no one can predict the environmental conditions that will occur in the future, the pessimistic view is that the northern stock will continue to decline and the optimistic view is that the present warm water conditions will herald increased recruitment. “

“Whichever occurs first, ” he adds, “the past, present and management team-­‐ recommended sardine harvest control rules were all designed to automatically regulate the exploitation rates both by reducing the quota and reducing the harvest rates as the stock declines, and by shutting down the fishery if the biomass falls below 150,000 mt. ”

The original sardine analysis, made in 1998, was updated by a new analysis that found offshore sea temperatures slightly better correlated with sardine productivity than the measurements made at Scripps Pier. Population simulations made with the updated information that included the population increase in recent decades show that the sardine stock is about 50% more productive than thought in 1998. The management team therefore recommended raising the upper bound of fishing fraction from 15 to 20 percent to account for the new best available science.

But that doesn’t mean that the catch quota for the coming year will be raised. This is a long-­‐term harvest control rule that simply follows better scientific modeling efforts.

The new rules will determine fishing rate just as before: If the temperature is cold, the harvest will be kept low; if the population size decreases both the harvest rate and the allowable catch will automatically decrease. In fact the new sardine harvest rule proposed by the sardine management team and enacted by the Council is actually more precautionary than the original rule it is replacing. It does this by producing an average long-­‐term population size at 75 percent of the unfished size, leaving even more fish in the water, vs. 67 percent in the original rule.

The original harvest rule reduced the minimum harvest rate to 5 percent during cold periods. The present, very complicated rule, has a minimum rate of 0 percent during cold periods.

What’s more, the harvest fraction will only be applied after subtracting 150,000 mt from the sardine biomass estimated in the next year’s stock assessment. The new harvest rule will still keep fishing limits low in cold-­‐water, low-­‐biomass conditions. The fraction won’t increase unless and until field surveys demonstrate more sardines and the ocean temperature increases substantially above recent levels.

Bottom line: The California sardine may be the best-­‐managed fishery of its type in the world -­‐ the poster fish for effective ecosystem-­‐based management.

D. B. Pleschner is Executive Director of the California Wetfish Producers Association, a nonprofit dedicated to research and to promote sustainable wetfish resources.

Subscribe and read the original article at SEAFOODNEWS.COM

Leave a Reply