appendix b final 2008 biological surveys of los angeles and long ...

3.0 Adult and Juvenile Fishes
3.4.1.3 Number of Species
A total of 62 species was collected with the otter trawl during all surveys (night and day
combined) (Table 3.4-1). The total number of species was virtually the same during the two
time periods (night = 52, day = 51), while comparisons among stations showed more species
collected on average at night (18) compared to day (13) (Table 3.4-2). The average number of
species collected per station varied from a low of 7 species during day surveys at inner harbor
Station LB14 to a high of 28 species at shallow-water Station LB2 during night surveys (Table
3.4-2).
Seasonal differences in the number of species are presented in Figure 3.4-2. Slightly more
species were collected at night during spring (April) and summer (July) surveys than winter
(January). The lowest number of species (31) was observed in night samples during winter.
3.4.1.4 Diversity and Dominance
Shannon-Wiener values were fairly consistent among stations and between day and night
surveys (Table 3.4-3). Values were generally higher during night surveys at most stations
compared to day and ranged from a low of 0.10 at Station LB14 (day) to a high of 2.24 during
day sampling at Station LA3. Margalef values followed similar trends, with night values being
consistently higher than day. Margalef values ranged from a low of 0.82 at Station LB14 (day)
to a high of 4.05 at Station LA3 (day survey). No depth-related or spatial patterns were
observed for any of the diversity indices.
Dominance values during all surveys ranged between 1 and 5, with most stations averaging a 3
(Table 3.4-3). High dominance values (3, 4, or 5) were found at stations and depths throughout
the harbors, and no spatial patterns were evident.
3.4.2 Dominant and Selected Species
Of the 62 species collected over all surveys and
stations in 2008, nine comprised nearly 93% of the
total catch. The dominant species in terms of
abundance were northern anchovy, white croaker,
queenfish, shiner surfperch, and white surfperch (Table
3.4-1). In addition, commercially/recreationally
important fish species collected during otter trawl
sampling included California halibut (Paralichthys
californicus) and barred sand bass (Paralabrax
nebulifer). Detailed information about some of the
dominant species is presented below.
Northern anchovy was the most abundant species
collected and represented nearly 30% of the total otter
trawl catch, but only less than 2% of the total biomass
(Table 3.4-1). This species was collected at every
sampling station and during every survey quarter, with
the highest numbers observed during day sampling.
Sizes ranged between 3 and 18 cm, with most
individuals between 4 and 8 cm (Figure 3.4-3). No spatial trends in sizes were evident and no
significant differences were found for average northern anchovy size among stations.
White croaker had the second highest abundance and represented 27% of the total trawl catch
and 38% of the biomass (Table 3.4-1). This species was collected during every sampling
quarter and at every station, with the highest numbers noted from night sampling. White
3–10 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010