262 



Coastul & Marine Ecosxstenis — Our Living; Resources 



Fig. 2. Changes in the relative 

 abundance of the 10 most numer- 

 ous fishes in the nearshore fish 

 assemblage of the Hudson River. 

 New York. 1974-89 (data from 

 Con Edison files). Changes in per- 

 centage abundance in (a) 5 diadro- 

 mous fish species and (b) 5 resi- 

 dent freshwater species. 



blueback hening in 1936 when this species was 

 taken at only 4 of the 112 sites sampled. In 

 1990. and during the last two decades, blueback 

 herring dominated the summer catches at 

 nearshore sites (Fig. 2). In the nearshore fish 

 assemblage of the Hudson River in 1974-89. the 

 five diadiomous species dominated throughout 

 the sample period (Fig. 2). 



[Blueback herring | Bay anchovy B| American shad 



^■striped bass ^lAlewife 



35 



30 



25 



S'20 



i 15 



10 



74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 

 Year 



IWhite perch | | Spoltail shiner ^H Banded killifish 

 liffiTessellated darter ■§ Pumpkinseed 



1 1 n 1 1 II i 



74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 

 Year 



Despite fluctuations in each of the most 

 abundant species, no obvious trends in relative 

 abundance were apparent although the relative 

 abundance of other species has changed. For 

 example, the abundance of Atlantic silverside 

 (Menidia menidia), a marine stray, has 

 increased, while other species, such as two res- 

 ident fish, emerald shiner {Nolvapis atheri- 

 noidcs) and goldfish (Ciinissii<s auratus), and 

 the diadronK)us rainbow smelt (Osmems mor- 

 dax). have dramatically decreased in relative 

 abundance (Fig. 3). Relative fish abundances 

 exhibited site, diel, and seasonal variation. 



I Atlantic silverside I I Emerald shiner 

 I Rainbow smelt ^H Goldlish 



80 



1974 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 

 Fig. 3. Annual trends in the abundance of four fish species 

 from the nearshore Hudson River assemblage. Rank is 

 based on total number of fish caught dunng the year; the 

 most abundant fish caught received a rank of 1 . the least 

 abundant a rank of 82. 



Implications of Changes 



Change in the nearshore fish assemblage of 

 the tidal portion of the Hudson River is contin- 

 uous. To identify trends in the abundance of an 

 assemblage made up of resident freshwater and 

 estuarine species, diadiomous fishes, and 

 marine strays, data must be collected in ways 

 that account for the dynamic qualities of the 

 species involved. Although the Hudson River is 

 among the most-studied aquatic systems in 

 North America, data necessary to confirm pop- 

 ulation trends in its fish assemblage are scant. 

 Abundance data are best for some commercial- 

 ly important and protected fishes. Data on other 



