Catch-per-unit-effort, environmental conditions and spawning migration of Cycleptus meridionalis Burr and Mayden in two coastal rivers of the northern Gulf of Mexico

Cycleptus meridionalis Burr and Mayden (Catostomidae) is a new species rece ntly distinguished from blue sucker C. elongatus in large rivers draining t o the northern Gulf of Mexico. Collections of this new species were taken f or 12 mo from the Pearl and Pascagoula rivers, Mississippi, to document cat ch-per-unit-effort, relationships with physical-chemical conditions and spa wning migration. We observed/collected 263 C. meridionalis in the Pearl Riv er on 14 dates and 296 in the Pascagoula River on 19 dates. River stage was highest between January and late April in both rivers and there was a nega tive relationship between (CPUE and river stage in both rivers. Highest CPU E of C. meridionalis was after May in both rivers when river stage decrease d and we consistently collected more C. meridionalis in the Pearl than the Pascagoula river. Stepwise multiple regression indicated C. meridionalis we re abundant in the Pascagoula River from summer through fall when conductiv ity was high and in fall and winter when water temperature was cooler and D O higher. In the Pearl River C. meridionalis were abundant when water was s hallow (summer and fall) and rainfall was high (April and May). Temporal patterns in the sex ratio were similar bt hc;een rivers from March to May. Males were more abundant early in the migration, becoming relative ly equal with females by May particularly in the Pascagoula River. Although males were more abundant from late-May until August in the Pearl river, fe males were more abundant between June and January in the Pascagoula river. Breeding tubercles were noted as early as 24 October, increased in both riv ers through 2 April and were generally absent for the remainder of the year Tagging results indicated only a 1.8 and 1.9% recapture rate in the Pearl and Pascagoula rivers, respectively. Only fish tagged in summer were recapt ured and they had moved upstream (3.2 km. Our observations indicate that C. meridionalis is viable in both rivers but this status may change if future river modification occurs, as happened with C. elongatus in other large ri ver systems.