Southern California Bight 2003 Regional Monitoring Program: IV. Demersal Fishes and Megabenthic Invertebrates
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- Species Areal Occurrence
- Species Abundance
- Species Biomass
Species CompositionTaxonomic CompositionA total of 142 species of fish, representing 3 classes and 52 families, were collected during the trawl survey (Appendix B-B13, Appendix F-F2, and Appendix F-F3). These consisted of 128 species of ray-finned fishes (Actinopterygii), 13 species of cartilaginous fishes (Chondrichthyes), and 1 species of hagfish (Myxini). The most diverse families were Scorpaenidae (rockfishes) with 25 species, Pleuronectidae (right-eye flounders) and Cottidae (sculpins) with 11 species each, Embiotocidae (surfperches) and Paralichthyidae (sand flounders) with 7 species each, and Agonidae (poachers) with 6 species. Two species, Colombian goby (Bollmannia gomezi) and whitetail tonguefish (Symphurus oligomerus) were taken for the first time in California during this survey. Species Areal OccurrenceOf 142 species, relatively few occurred over a large proportion of the mainland shelf of the SCB. The equitability curve for areal occurrence was hyperbolic with a step-like appearance. The curve shows a relatively smooth change in slope with gradual decreasing percent of area to the right (Figure IV-5; Appendix B-B14). Individually, 21 species (15% of all species) occurred in over 20% and only 2 (Dover sole, Pacific sanddab) in over 50% of the total area (Table IV-9). The 5 most widely distributed species were Dover sole, Pacific sanddab, English sole (Parophrys vetulus), slender sole, and stripetail rockfish (Sebastes saxicola). and a mean of 6 species occurred in more than 50% of the area of each shelf zone. Among the mainland and island regions, the southeast Channel Islands had the highest 5 most widely distributed species were Dover sole, Pacific sanddab, English sole (Parophrys vetulus), slender sole, and stripetail rockfish (Sebastes saxicola). and a mean of 6 species occurred in more than 50% of the area of each shelf zone. Among the mainland and island regions, the southeast Channel Islands had the highest Thirty species occurred in more than 50% of the area in at least one subpopulation (Table IV-10). A mean of 6 species occurred in more than 50% of the area of each subpopulation in the mainland and island regions, number of species (15) while the northern and southern mainland regions had the lowest (both with 2). Among the 5 shelf zones, the middle shelf had the highest number of species (13) occurring in 50% or more of the area and the bays and harbors had the least (1). Geographically, Dover sole was the most common species in the northern and southern mainland regions; hornyhead turbot was the most common species in the central region; Pacific sanddab was most common in the northwest Channel Islands; and Pacific sanddab, plainfin midshipman (Porichthys notatus), and shortspine combfish (Zaniolepis frenata) were most common in the southeast Channel Islands. Bathymetrically, Dover sole was the most common species in the upper slope zone, Dover sole and slender sole were most common in the outer shelf, Pacific sanddab was most common in the middle shelf, speckled sanddab in the inner shelf, and California halibut in the bays and harbors. The most widespread species, Dover sole, inhabited more than 50% of the area in all subpopulations except bays and harbors and inner shelf. The next most widespread species in this regard were Pacific sanddab (6 subpopulations), and English sole and stripetail rockfish (4 subpopulations). Sixteen species occurred in more than 50% of the area of only a single subpopulation (by region and depth). Regional or shelf zone specificity occurred in pygmy poacher (Odontopyxis trispinosa) and lingcod (northwest Channel Islands); spotted cusk-eel (Chilara taylori), curlfin sole, cowcod (Sebastes levis), chilipepper (Sebastes goodei), and spotfin sculpin (Icelinus tenuis) (southeast Channel Islands); California halibut (bays and harbors); speckled sanddab (inner shelf); roughback sculpin (Chitonotus pugetensis) (middle shelf); rex sole (Glyptocephalus zachirus), blacktip poacher (Xeneretmus latifrons), and blackbelly eelpout (Lycodes pacificus) (outer shelf); and splitnose rockfish (Sebastes diploproa), Pacific hake (Merluccius productus), and bigfin eelpout (Lycodes cortezianus) (upper slope). Species AbundanceThe equitability curve of species abundance approximated a tight hyperbola (Figure IV-5), indicating that relatively few species dominated the overall abundance. There was a sharp change of slope at about species 15, with those ranking to the left sharply increasing in abundance and those to the right gradually decreasing (Figure IV-5; Appendix B-B15). The 36 most abundant species (25% of all species) together accounted for 95% of abundance in the survey (Table IV-11). Four species accounted for approximately 50% of the total fish abundance: Pacific sanddab, speckled sanddab, slender sole, and yellowchin sculpin (Icelinus quadriseriatus). Combinations of 25 species comprised the top 80% of the abundance in each subpopulation (Table IV-12), with a mean of 9 species per subpopulation in the mainland and island regions. A mean of 7 species per subpopulation comprised 80% of the abundance in the shelf zones. On the mainland shelf, species comprising 80% of the abundance per region were similar among northern, central, and southern regions (12, 11, and 12, respectively), while northwest and southeast islands were much lower (6 and 5, respectively). Within the depth zones, the bays and harbors had the highest number of species (11), comprising 80% of the abundance. Fewer species made up this abundance on the shelf and slope zones (6-7 species). Pacific sanddab was the most abundant species in the central, southern, and island regions. Speckled sanddab was the most abundant species in the northern mainland region and within the inner shelf zone. Slender sole was the most abundant species within the outer shelf and upper slope zones. Longspine combfish (Zaniolepis latipinnis) was most abundant within the middle shelf, and white croaker (Genyonemus lineatus) was the most abundant species in bays and harbors. Table IV-9. Demersal fish species occurring in 20% or more of the area in the regional survey of the mainland shelf and slope of southern California at depths of 5-202 m, July - October, 2003. 
Table IV-10. Demersal fish species comprising 50% or more of the area by subpopulation on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Table IV-11. Demersal fish species comprising 95% or more of the total fish abundance on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Table IV-12. Demersal fish species comprising 80% or more of the fish abundance by subpopulation on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Figure IV-5. Equitability curves of fish occurrence, abundance, and biomass by species at depths of 2-476 m, Southern California Bight 2003 Regional Survey, July-October 2003. x=140th species. Species BiomassThe equitability curve of species biomass approximated a tight hyperbola, similar to that for species abundance (Figure IV-5), although the curve for biomass was slightly less concave than the curve for species abundance. There was a sharp change of slope at about species 5, with those ranking to the left sharply increasing in biomass and those to the right gradually decreasing (Figure IV-5; Appendix B-B16). As with the abundance curve, relatively few species dominated the overall biomass. Forty-eight species (34 % of all species) accounted for the top 95% of biomass in the survey (Table IV-13). Seven species accounted for approximately 50% of the total fish biomass: Pacific sanddab, slender sole, California halibut, queenfish (Seriphus politus), Dover sole, English sole, and round stingray (Urobatis halleri). Combinations of 35 species also made up the top 80% of the biomass in each subpopulation (Table IV-14), with a mean of 13 species per subpopulation in the mainland and island regions and a mean of 9 species in the shelf zones. More species comprised 80% of the biomass in the northern, central, and southern mainland regions (15, 17, and 17, respectively) than did the northwest and southeast Channel Islands (10 and 5, respectively). Among the shelf zones, inner and middle shelf zones had the highest number of species (both 12), while bays and harbors, outer shelf, and upper slope depths zones were less (7, 7, and 8, respectively). Geographically, Pacific sanddab was the biomass dominant in all mainland and island regions. Bathymetrically, biomass was dominated by queenfish in bays and harbors, by California halibut on the inner shelf, Pacific sanddab on the middle and outer shelf, and Dover sole on the upper slope. Directory: pub -> download pub -> Acm word Template for sig site pub -> The german unification, 1815-1870 pub -> Baltic Olympiads in Informatics: Challenges for Training Together pub -> Preparation of Papers for ieee transactions on medical imaging pub -> Forthcoming meetings and conferences pub -> Asilomar Conference on Circuits, Systems & Computers, Pacific Grove, ca, November 1978, pp. 55 58 pub -> Forthcoming meetings and conferences pub -> Harmonised compatibility and sharing conditions for video pmse in the 7 9 ghz frequency band, taking into account radar use Download 11.21 Mb. Share with your friends:
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