Cycleptus meridionalis Burr and Mayden (Catostomidae) is a new species recently distinguished from blue sucker C. elongatus in large rivers draining to the northern Gulf of Mexico. Collections of this new species were taken for 12 mo from the Pearl and Pascagoula rivers, Mississippi, to document catch-per-unit-effort, relationships with physical-chemical conditions and spawning migration. We observed/collected 263 C. meridionalis in the Pearl River 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 negative relationship between CPUE and river stage in both rivers. Highest CPUE of C. meridionalis was after May in both rivers when river stage decreased and we consistently collected more C. meridionalis in the Pearl than the Pascagoula river. Stepwise multiple regression indicated C. meridionalis were abundant in the Pascagoula River from summer through fall when conductivity was high and in fall and winter when water temperature was cooler and DO higher. In the Pearl River C. meridionalis were abundant when water was shallow (summer and fall) and rainfall was high (April and May).
Temporal patterns in the sex ratio were similar between rivers from March to May. Males were more abundant early in the migration, becoming relatively equal with females by May, particularly in the Pascagoula River. Although males were more abundant from late-May until August in the Pearl river, females were more abundant between June and January in the Pascagoula river. Breeding tubercles were noted as early as 24 October, increased in both rivers 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 recaptured 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 river systems.