NUTRIENT REMOVAL BY AGE-0 ATLANTIC MENHADEN (BREVOORTIA-TYRRANUS) IN CHESAPEAKE-BAY AND IMPLICATIONS FOR SEASONAL MANAGEMENT OF THE FISHERY

Yearly migrations of catadromous herbivorous fish such as the Atlantic menhaden (Brevoortia tyrranus) may constitute a significant mechanism for the transport of organic materials out of estuarine areas. Assess ments of nutrient budgets in these estuaries, including Chesapeake Bay , acknowledge the potential importance of this mechanism but exclude i t from quantitative analyses because few data exist. Advances in the u nderstanding of bioenergetic processes of many species of fish and dev elopment of tools to simulate fish consumption and growth provide an o pportunity to quantify the importance of fish dynamics in ecosystem pr ocesses. This paper presents a STELLA simulation model of age-0 Atlant ic menhaden bioenergetics and fishery dynamics over a single season us ing field and laboratory data from the literature. The model simulates growth and consumption of age-0 Atlantic menhaden over a 183 day peri od during which they are abundant in Chesapeake Bay. A fishery managem ent submodel is used to investigate the effects of changing fishing mo rtality dynamics. The monetary value of the fishery is estimated as a traditional commodity and in terms of the ecological service it provid es as a consumer of the products of eutrophication. The simulation sho ws that age-0 Atlantic menhaden could consume 1.5-119% of total annual primary productivity in Chesapeake Bay and that seasonal harvesting a t present levels has a moderate effect on the level of consumption tha t could potentially be exhibited by the fish at its present estimated population size. (C) 1998 Elsevier Science B.V. All rights reserved.