Ecology of fishes in Upper Newport Bay, California: seasonal dynamics and community structure

Horn, Michael H. and Allen, Larry G. (1981) Ecology of fishes in Upper Newport Bay, California: seasonal dynamics and community structure. Long Beach, CA, California Department of Fish and Game, (Marine Resources Technical Report, 45)

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A total of 366 bimonthly (January 1978-January 1979) samples taken with six types of gear (otter trawl, gill net, bag seine, small seine, drop net, square enclosure - all with replication except the gill net) at four stations in upper Newport Bay, California yielded 51,816 fishes belonging to 46 species and weighing over 353 kg. Atherinops affinis (topsmelt) was the most abundant species accounting for 76% of total individuals. Seven species, all of low trophic levels, made up over 97% of the total catch. Mugil cephalus (striped mullet) ranked first in biomass (= 36% of the total) with six species accounting for more than 80% of the total biomass. The largest number of individuals (71%) was collected with the bag seine, the greatest number of species (35) was captured with the otter trawl and the largest percentage of the biomass (56%)was obtained with the gill net. Species richness, number of individuals and biomass were lowest in January (1978 or 1979) or March and highest in July (numbers, biomass) or September (species). Bimonthly diversity (H') values ranged from 0.48 to 2.17 (overall value 1.05) and tended to be inversely related to abundance levels. Species richness was greatest at Station 4 (the lowermost station) and least at Station 1 (the uppermost station). Numbers of individuals and biomass peaked at Station 2 and reached lowest levels at Station 1. Length-frequency analysis of six of the most abundant species indicated utilization of the upper bay by two or more stages in the life history of these species. More than 92,000 eggs belonging to seven taxa and an unknown category and 426 larvae from 20 taxa were collected with a 0.5 m net mounted on an epibenthic sled during the same bimonthly periods and at the same stations as the juvenile/adult samples. Most of the eggs were collected at Station 2 in May with the numbers overwhelmingly dominated by those of Anchoa compressa (deepbody anchovy) (99.7% of total numbers). The most abundant larva was that of Clevelandia ios (arrow goby). Nearly 60% of the total larval catch was made up of members of the family Gobiidae. Larval taxa and individuals were fewest in January (1978). The number of taxa was highest in March, September and January (1979) whereas larval numbers peaked in May. The number of taxa and of individual larvae varied only slightly among the four stations. Asymptotic species accumulation curves indicated adequate sampling of juvenile/adult fishes. Cluster analysis produced eight species groups of resident and periodic species that variously utilize the three main habitats (channel, inshore, pannes) in the upper bay. Species richness and abundance were positively correlated with both temperature and salinity. Temperature, salinity and depth of capture were frequently correlated with individual species abundances and were used in combination to partially explain the spatial utilization of species and species groups. The upper bay fish community is important and worthy of preservation for at least three reasons: 1) it contains species assemblages not duplicated in any other coastal environment; 2) it contains life history stages of a variety of coastal fish species; and 3) it contains large populations of small, low-trophic level species and juveniles of other species which serve as forage for larger, predatory species that are frequently of economic importance. Members of the fish community respond noticeably to altered environmental conditions such as the heavy rainfall (and accompanying low salinity and high turbidity) that occurred during the early months of 1978. The short and long term, as yet often unpredictable, fluctuations in the populations emphasize the need for periodic monitoring and for the development of a mathematical model of the fish community if it is to be thoroughly understood and properly managed. (102pp.)

Item Type: Monograph or Serial Issue
Title: Ecology of fishes in Upper Newport Bay, California: seasonal dynamics and community structure
Personal Creator/Author:
Horn, Michael H.
Allen, Larry G.
Series Name: Marine Resources Technical Report
Number: 45
Date: 1981
Publisher: California Department of Fish and Game
Place of Publication: Long Beach, CA
Latitude: 33.3832
Longitude: 117.531
Issuing Agency: California Department of Fish and Game
Uncontrolled Keywords: fish; ecology; Newport Bay; California; Atherinops affinis; topsmelt; Mugil cephalus; striped mullet; deepbody anchovy; Anchoa compressa; arrow goby; Clevelandia ios
Subjects: Ecology
Item ID: 714
Depositing User: Joan Parker
Date Deposited: 23 Feb 2008 19:53
Last Modified: 29 Sep 2011 21:40

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