Competition between juvenile striped bass and bluefish: resource partitioning and growth rate

Abstract

The potential for competition to influence the population dynamics of bluefish Pomatomus saltatrix and striped bass Morone saxatilis through interactions at the juvenile stage was examined. Habitat and diet utilization were compared between juvenile striped bass and bluefish in 3 New York Bight marine embayments. Juvenile bluefish and striped bass were seldom captured together during the summer and early fall, suggesting low habitat overlap at the scale of a beach seine haul. Diet overlap was also low; age-0 bluefish (spring-and summer-spawned cohorts) had a more piscivorous diet than age-0 and age-1 striped bass. A 60d laboratory growth experiment tested for interference competition between age-0 bluefish (spring-spawned) and age-1 striped bass fed fish prey in mixed-and single-species treatments. In the growth experiment, bluefish grew significantly faster than striped bass; however, within a species, there was no significant difference in growth between the mixed-and single-species treatments. Additionally, long-term field-monitoring data showed that annual estimates of growth rate for bluefish and striped bass were not correlated with annual estimates of their potential competitor's density. These field and laboratory data provide no evidence for competitive interactions between juvenile striped bass and bluefish.