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

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. (C) 1998 Elsevier Science B.V. All rights reserved.