Effects of the presence of herring ( Clupea harengus) on the stock-recruitment relationship of Barents Sea capelin ( Mallotus villosus)

Abstract

The relationship between spawning stock biomass (SSB) and number of recruits was studied for the year classes 1972–1996 of the Barents Sea capelin ( Mallotus villosus) stock. The observations did not fit a Beverton–Holt function very accurately. A considerable improvement in the fit was obtained when all years with young herring ( Clupea harengus) present in the Barents Sea was left out of the analysis. Young herring was found to have a negative influence on the capelin recruitment. An even better fit was obtained when the abundance of 1-year old and older, herring was included as a term in a modified Beverton–Holt equation, letting the amount biomass of herring affect the half-value, but not the maximum recruitment. The spawning stock-recruitment relationship found in this paper can be used directly in multispecies models of management relevance.