Rainbow Smelt Spawning Monitoring
PROGRESS REPORT State: NEW HAMPSHIRE Grant: F-61-R-22/F19AF00061 Grant Title: NEW HAMPSHIRE’S MARINE FISHERIES INVESTIGATIONS Project I: DIADROMOUS FISH INVESTIGATIONS Job 2: MONITORING OF RAINBOW SMELT SPAWNING ACTIVITY Objective: To annually monitor the Rainbow Smelt Osmerus mordax resource using fishery independent techniques during their spawning run in the Great Bay Estuary. Period Covered: January 1, 2019 - December 31, 2019 ABSTRACT In 2019, a total of 844 Rainbow Smelt Osmerus mordax (349 in Oyster River, 405 in Winnicut River, and 90 in Squamscott River) were caught in fyke nets. The CPUE in 2019 was highest in the Oyster River with 23.79 smelt per day, whereas the Winnicut River (8.46 smelt per day) and Squamscott River (5.54 smelt per day) were lower. A male-skewed sex ratio was observed at all rivers, a likely result of differences in spawning behavior between sexes. The age distribution of captured Rainbow Smelt, weighted by total catch was highest for age-2 fish, followed by age-1, age-3, and age-4 fish. Most water quality measurements (temperature, dissolved oxygen, specific conductivity, and pH) were within or near acceptable ranges for smelt spawning and egg incubation and development in 2019; however, turbidity was above the threshold in the Oyster River for most days monitored. INTRODUCTION Rainbow Smelt Osmerus mordax are small anadromous fish that live in nearshore coastal waters and spawn in the spring in tidal rivers immediately above the head of tide in freshwater (Kendall 1926; Murawski et al. 1980; Buckley 1989). Anadromous smelt serve as important prey for commercial and recreational culturally valuable species, such as Atlantic Cod Gadus morhua, Atlantic Salmon Salmo salar, and Striped Bass Morone saxatilis (Clayton et al.
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