Southern California Bight 2003 Regional Monitoring Program: IV. Demersal Fishes and Megabenthic Invertebrates
Combined Fish and Invertebrate Assemblages
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Combined Fish and Invertebrate AssemblagesCombined Fish and Invertebrate Recurrent GroupsRecurrent group analysis at the 0.50 level of affinity identified 60 recurrent groups of combined fishes and invertebrates consisting of 2-10 species per group with 11 associate species (Figure VI-11a; Table VI-7; Appendix D-D8). In all, the groups and associates included 87 (19%) of the 450 species collected in the survey. Recurrent groups were found at 1-36 stations; 34 of the 60 groups occurred at only 1 site (Appendix D-D8), with 17 at 2-10 sites, and 9 at 11-36 sites (Figures VI-11a and VI-11b; Table VI-7). The major recurrent groups generally differed in depth distribution, with most occurring in one or two of the four predetermined shelf zones (Table VI-4). The more widespread groups are likely to represent important assemblages. While groups occurring with low frequency may provide some useful biological information on species associations, some may be due to chance. The most widespread recurrent groups occurring at more than 10 stations will be discussed in detail below. Table VI-5. Frequency of occurrence (number of stations) of megabenthic invertebrate site clusters by region and subpopulation on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Figure VI-8. Summary of megabenthic invertebrate cluster analysis and relationships among site and species clusters on the southern California shelf at depths of 2-476 m, July- October 2003. 
Figure VI-9. Bathymetric distribution of megabenthic invertebrate site clusters on the southern California shelf at depths of 2-476 m, July-October 2003. Table VI-6. Frequency of occurrence (percent of stations) of megabenthic invertebrate species occurring at 50% or more of the stations in at least one site cluster on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Table VI-7. Mean and range of depth of combined demersal fish and megabenthic invertebrate recurrent groups on the southern California shelf and upper slope, July-October, 2003. 
Figure VI-10. Distribution of megabenthic invertebrate site cluster on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. Group 13–Harbor/Inner Shelf Croaker Group. This group is the same as Group 2 in the fish recurrent group results above (Figure VI-1). It consisted of two schooling sciaenid species, white croaker and queenfish (Figures VI-1 and VI-11b). This group occurred at 12 stations on the soft bottom inner shelf at depths of 8-30 m (mean=17 m; Table VI-7). It was found in the LA/LB Harbor (5 stations), near the Santa Clara and Ventura river mouths (4 stations), as well as in the San Diego County region (3 stations). It was not found on the islands. Although in the fish recurrent group analysis, Group 2 did not have affinities with other recurrent groups, Group 13 in combined fish and invertebrates was associated with Group 14 (Figure VI-11b). It was not associated at the affinity level used in the analysis with any invertebrate species. Group 14–Inner Shelf Shrimp/Sanddab Group. This group consisted of two species, speckled sanddab and blackspotted shrimp (Figure VI-10). It occurred at 29 stations on the soft bottom inner shelf at depths of 11-30 m (mean=19 m; Table VI-7). It was found on the mainland inner shelf from north to south and in LA/LB Harbor (4 stations). Group 14 was associated with Groups 13 and 25 (Figure VI-11b). Group 25–Middle Shelf Fish/Sand Star Group. This group consisted of 10 species, 9 fishes (Pacific sanddab, yellowchin sculpin, longspine combfish, longfin sanddab, pink seaperch, roughback sculpin, California tonguefish, hornyhead turbot, and bigmouth sole) and 1 invertebrate (California sand star; Figure VI-11b). The fish portion of the group was the same as Group 4 in the fish recurrent group analysis (Figure VI-1). It occurred at 16 stations on the middle shelf at depths of 34-81 m (mean=51 m; Table VI-7). It was found on the mainland middle shelf, primarily in the central region, at LPOTW and Non-LPOTW areas. Group 25 had 9 associate species, (California blade barnacle, New Zealand papperbubble, yellow sea twig, pygmy poacher, lingcod, English sole, California scorpionfish, California lizardfish, and halfbanded rockfish) and was associated with Groups 14, 29, 41, and 43 (Figure VI-10). Group 29–Middle Shelf Sea Cucumber/Goby Group. This group consisted of 2 species: California sea cucumber and bay goby (Figure VI-11b). It occurred at 31 stations on the middle shelf at depths of 25-92 m (mean=59 m; Table VI-7). It was found on the mainland middle shelf, primarily in the central and southern regions, at SPOTW, LPOTW, and Non-POTW areas. Group 29 had 2 associate species (yellow sea twig and halfbanded rockfish) and was associated with Group 25 (Figure VI-11b). Group 35–Middle Shelf Fish/Sea Pen/Echinoderm Group. This group consisted of 6 species, 4 invertebrates (white sea urchin, trailtip sea pen, brokenspine brittlestar, gray sand star), and 2 fishes (stripetail rockfish, plainfin midshipman; Figure VI-11b) It occurred at 13 stations on the middle shelf at depths of 56-110 m (mean=88 m; Table VI-7). It was found on the mainland (9 stations) and islands (4 stations). Group 35 had 4 associate species (yellow sea twig, halfbanded rockfish, Pacific spiny brittlestar, eastern Pacific bobtail) and was associated with Groups 25, 29, 41, 43, and 47 (Figure VI-11b). Group 41–Middle Shelf/Outer Shelf Shrimp/Dover Sole /Octopus Group. This group consisted of 3 species, 2 invertebrates (ridgeback rock shrimp, red octopus), and 1 fish (Dover sole; Figure VI-11b) It was the most widespread recurrent group, occurring at 36 stations on the middle shelf and outer shelf at depths of 42-204 m (mean=110 m; Table VI-7). It was found on the mainland (all regions, POTW, and non-POTW areas) and islands. Group 41 had associate species (pygmy poacher, English sole, halfbanded rockfish, eastern Pacific bobtail) and was associated with Groups 25, 43, and 50 (Figure VI-11b). Group 43–Middle Shelf/Outer Shelf Combfish/Rockfish Group. This group consisted of 2 species: shortspine combfish and greenstriped rockfish (Figure VI-11b) In the fish recurrent group analysis, shortspine combfish was a member of Group 7 and greenstriped rockfish was an associate to Groups 5 and 7 (Figure VI-1). Group 43 occurred at 25 stations on the middle shelf and outer shelf at depths of 76-202 m (mean=125 m; Table VI-7). It was found on the mainland and at islands. Group 43 was associated with Groups 25, 41, 47, and 50 (Figure VI-11b). Group 47–Outer Shelf/Upper Slope Shrimp/Poacher/Eelpout Group. This group consisted of 4 species, 2 invertebrates (moustache bay shrimp, flagnose bay shrimp) and 2 fishes (blacktip poacher, blackbelly eelpout) (Figure VI-10). Group 47 occurred at 11 stations on the outer shelf and upper slope at depths of 120-322 m (mean=176 m; Table VI-7). It was found on the mainland (all regions) and at the northwest Channel Islands. Group 47 had an associate species (eastern Pacific bobtail) and was associated with Groups 35 and 43 (Figure VI-11b). Group 50–Outer Shelf/Upper Slope Flatfish/Sea Urchin Group. This group consisted of 3 species, 1 invertebrate (fragile sea urchin) and 2 fishes (slender sole, rex sole; Figure VI-11b). Group 50 occurred at 24 stations on the outer shelf and upper slope at depths of 132-469 m (mean=233 m; Table VI-7). It was found on the mainland (all regions) and at the northwest Channel Islands. Group 50 had an associate species (bluebarred prickleback) and was associated with Groups 43 and 51 (Figure VI-11b). 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