Alternate Title

Characterization of Ichthyoplankton in the Northeastern Gulf of Mexico from Seamap Plankton Surveys, 1982-1999

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Data for 61 selected ichthyoplankton taxa from 1,166 bongo and neuston net samples at 72 stations comprising the USGS Northeastern Gulf of Mexico Ichthyoplankton Synopsis (UNIS) study area were analyzed. These data were taken during annual spring and fall Southeast Area Monitoring and Assessment Program (SEAMAP) Gulfwide plankton surveys over the period 1982-1999. The UNIS study area contributed disproportionately more fish eggs, total larvae and net-caught zooplankton biomass to survey totals than would be expected from the number of samples taken in the study area. This pattern was more evident during spring than fall surveys and is probably related to the close proximity of UNIS study area stations to the Mississippi River and the inshore penetration of nutrient rich deep slope water via the DeSoto Canyon. Statistical comparison of the percent frequency of occurrence of the 61 selected taxa revealed that the larvae of many were taken significantly more often in the UNIS study area than expected based on their occurrence Gulfwide. Thirteen of these taxa were taken more often in the study area during the season and collecting gear combination that accounted for the highest catches. These taxa represented fishes from mesopelagic, continental shelf, and reef assemblages reflecting the wide diversity of habitats available in the northeastern Gulf of Mexico. Distinct distribution patterns were observed among larvae in the UNIS study area that appear to be associated with the presence of the DeSoto Canyon. The consistent presence of fish eggs throughout the UNIS study area at mean abundances exceeding 100 eggs under 10 m² sea surface indicates that this region of the Gulf of Mexico is an important spawning area.

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