Stock and Recruitment

Abstract

The most important and generally most difficult problem in biological assessment of fisheries is the relationship between stock and recruitment. If there were no repeatable relationship between spawning stock and resultant recruitment, then managers would only need to worry about optimization of yield per recruit. There would be no need to worry about complex and expensive regulations to prevent overfishing, except in terms of the relatively simple matter of preventing fish from being caught at sizes so small as to be wasteful in terms of potential production from body growth. The history of fisheries management would be much different. The classic stories of fisheries management, from the history of blue whales (Sibbaldus musculus) to California sardines (Sardinops sagax) to Peruvian anchoveta (Engraulis ringens) are all stories of stocks fished so hard that recruitment was greatly reduced and the stocks collapsed. Cushing (1971) identified four stocks which he felt had collapsed due to overfishing: the Hokkaido-Sakhalin herring (Clupea harengus), the Norwegian herring (Clupea harengus), the Japanese sardine (Sardinops melanosticta), and the California sardine (Sardinops sagax)