An assessment of the feeding success of young-of-the-year winter flounder (Pseudopleuronectes americanus) near a municipal pier in the Hudson River estuary, U.S.A.

Abstract

We examined feeding success of young-of-the-year winter flounder (Pseudopleuronectes americanus Walbaum) (20–50 mm TL) around a large, municipal pier in the Hudson River estuary, USA. Replicate, 3-h feeding experiments were conducted using benthic cages (0.64 m²) deployed under, at the edge, and outside of the pier during late spring and early summer in 1998 and 1999. Significantly more winter flounder caged under piers had empty stomachs ($\bar x$=71.9%) than at the edge or in open water ($\bar x$=29.2% and 14.4%, respectively). Feeding intensity was significantly higher outside of the pier ($\bar x$=0.40%) than the edge or under the pier ($\bar x$=0.19% and 0.03%, respectively). Simultaneous with feeding experiments, benthic core samples were collected adjacent to cages. Variability was high, but abundances of prey were consistently higher under the pier ($\bar x$=200.14±113.3 SD in 1998; 335±290.2 in 1999) than at the edge ($\bar x$=126.6±50.2 in 1998; 70.8±68.5 in 1999) or in open water ($\bar x$=53.4±16.1 in 1998; 123.8±193.9 in 1999). No significant differences in prey biomass were determined, suggesting that small, numerous prey were available under the pier and fewer, larger taxa were present at the edge and outside. Data indicate that feeding is suppressed among young-of-the-year winter flounder caged under piers in spite of sufficient prey available. Based on these and other experiments we submit that areas under piers are not suitable long-term habitats for juvenile fish because they interfere with normal feeding activities.