Fish Bulletin No. 101. Age Determination of the Northern Anchovy, Engraulis mordax
- Author(s): Miller, Daniel J
- et al.
With the rapid decline of the sardine fishery beginning in 1946–47, California fishermen and processors turned to substitute species. One of these was the northern anchovy (Engraulis mordax). Until 1947, anchovies had been used for bait almost exclusively and the annual catch had seldom exceeded 5,000 tons. Between 1947 and 1951 these fish were canned in moderate amounts and the landings varied from 5,000 to 12,000 tons. In 1952 the tonnage increased to 34,000 and in 1953 to 49,000.
The major part of the anchovy canning has been done by the processors at Monterey. In this Central California area anchovies are also used in small quantities for dead bait. Along the Southern California coast for many years there has been a thriving live bait anchovy fishery. This bait is used chiefly by sport fishermen and in more limited amounts by the commercial men. The live bait anchovy catch of Southern California increased from about 2,000 tons in the early forties to more than 6,000 tons in 1953.
Because of the use of these fish for live bait and because anchovies are an important forage fish for the larger species fished extensively in California waters by both sport and commercial fishermen, much concern has been expressed over the rapid expansion of the anchovy canning industry. Several plans for control of this expanding fishery have been proposed and the California Fish and Game Commission has refused permits to use anchovies for reduction into meal and oil and has established case pack requirements. Continued public pressure for more stringent regulations made evident the need for basic biological information about this species. To supply this need the Department of Fish and Game increased its investigations on the anchovy and the Cooperative Oceanic Fisheries Investigation added this species to its program of studies. Only by such methods will a solution to the problems of population dynamics be reached and made applicable to management.
Clark and Phillips (1952) published results of the anchovy studies from 1946 through 1951. This introductory work indicated the need for intensive research on certain aspects of the anchovy life history. The most important and difficult was the development of a reliable method for age determination. The responsibility for this fell to the biologists conducting the routine sardine age analysis, two from the California Department of Fish and Game and two from the U. S. Fish and Wildlife Service.
The program of anchovy sampling was expanded to include all California ports of landing. Since northern anchovy and Pacific sardine scales are similar in type and structure, the anchovy commercial catch sampling and age analysis was conducted in a manner similar to that adopted for the Pacific sardine and the anchovy age determinations were made as soon as the collections were completed for the season.
The usual procedure in conducting a routine age analysis of a newly studied species is to first complete preliminary studies relative to the reliability of the method as applied to that species. For the anchovy these special studies were conducted simultaneously with the collection and analysis of the first two seasons' catch. If the results of these special studies indicated that anchovy scales could not be read with a sufficient degree of reliability then the routine age analysis would be discontinued. This bulletin presents the results of these special studies and the age and length composition of the 1952–53 and the 1953–54 catch.
Here are given the reasons for considering valid the method used to interpret the age from the scales of the anchovy. The errors inherent in the method are pointed out and the reliability that can be placed on the findings is indicated. Given also are the tonnages and numbers of anchovies taken in the canning catch in the 1952–53 and 1953–54 seasons. No fish older than six years was found. In 1952–53 more than half of the catch came from the 1950, 1951 and 1952 year classes, anchovies less than three years old. In 1953–54 fish under three years (the 1951, 1952 and 1953 year classes) comprised more than 80 percent of the catch. These data suggest that the anchovy is a relatively short lived fish and that the population is subject to comparatively rapid turnover.