Comment to Pacific Fishery Management Council
INFORMATION COMPILED BY DR. RICHARD PARRISH
“The reason that the sardine population has declined so rapidly in the last few years is exceedingly simple. The story is easily seen in the figures I have attached here.
There was a very poor year-class in 2010 followed by 3 years of total recruitment failure. Both the sardine stock assessment and the Acoustic-Trawl series clearly show this. End of story.
The sardine control rule did exactly what it was designed to do. It has shut down the directed fishery after a series of poor recruitment years. — Richard Parrish
Sardine recruitment in billions of one-year-old fish; 2010 was a very poor reproductive year and it was followed by three years of complete reproductive failure (2011, 12, 13). The estimate for 2014 is a statistical forecast based on the average recruits per spawner. Few 2014 sardines have been observed. (Hill et al 2015 Sardine Stock Assessment)
The spawning stock biomass fell from about 600,000 mt in 2010 to a bit over 100,000 mt in 2015. With no recruitment, biomass drops very fast with or without a fishery. The same thing happened in the Japanese Sardine fishery about 20 years ago.
Here is the Acoustic survey data showing again the complete reproductive failure in the 2011-13 year classes.
Sea Lion pups are starving in Southern California and Oceana claims it is due to overfishing of sardine. Here are the food habits of sardine. They are 8th in abundance in the California sea lion diet.
Lowry, M. S. and J. V. Carretta. 1999. Market squid (Loligo opalescens) in the diet of California sea lions (Zalophus californianus) in southern California (1981-1995). CalCOFI Rep. 40:196-207.
Here is the time series of sea lion pups. This is used as the primary population index. The most recent total estimate is as follows: (from CALIFORNIA SEA LION (Zalophus californianus ): U.S. Stock. Revised 12/15/2011)
POPULATION SIZE
The entire population cannot be counted because all age and sex classes are not ashore at the same time. In lieu of counting all sea lions, pups are counted during the breeding season (because this is the only age class that is ashore in its entirety), and the number of births is estimated from the pup count. The size of the population is then estimated from the number of births and the proportion of pups in the population. Censuses are conducted in July after all pups have been born. To estimate the number of pups born, the pup count for rookeries in southern California in 2008 (59,774) was adjusted for an estimated 15% pre-census mortality (Boveng 1988; Lowry et al. 1992), giving an estimated 68,740 live births in the population. The fraction of newborn pups in the population (23.2%) was estimated from a life table derived for the northern fur seal (Callorhinus ursinus) (Boveng 1988, Lowry et al. 1992) which was modified to account for the growth rate of this California sea lion population (5.4% yr-1, see below). Multiplying the number of pups born by the inverse of this fraction (4.317) results in a population estimate of 296,750.
Minimum Population Estimate
The minimum population size was determined from counts of all age and sex classes that were ashore at all the major rookeries and haul-out sites in southern and central California during the 2007 breeding season. The minimum population size of the U.S. stock is 153,337 (NMFS unpubl. data). It includes all California sea lions counted during the July 2007 census at the Channel Islands in southern California and at haul-out sites located between Point Conception and Point Reyes, California. An additional unknown number of California sea lions are at sea or hauled out at locations that were not censused.
Current Population Trend
Trends in pup counts from 1975 through 2008 are shown in Figure 2
INFORMATION COMPILED BY CWPA
ALLOWING AN ADEQUATE INCIDENTAL SARDINE CATCH IN OTHER CPS FISHERIES IS CRITICAL TO SUSTAIN CALIFORNIA’S WETFISH INDUSTRY
