. Commercial fisheries review. Fisheries; Fish trade. 40. Fig. 6 - Threadherring gilled in a 2-inchmonofilament gill net. Samples have been collected from the com- mercial catch since the beginning of the fish- ery off Fort Myers. A systematic port sampling program is beyond our means at present, but the fishermen have been cooper- ative in preserving samples from individual purse-seine catches. Fishing log books and charts were provided for all vessels engaged in the fishery to document catches, effort, and fishing areas. Laboratory processing of fish samples in- cludes measurements of body l
. Commercial fisheries review. Fisheries; Fish trade. 40. Fig. 6 - Threadherring gilled in a 2-inchmonofilament gill net. Samples have been collected from the com- mercial catch since the beginning of the fish- ery off Fort Myers. A systematic port sampling program is beyond our means at present, but the fishermen have been cooper- ative in preserving samples from individual purse-seine catches. Fishing log books and charts were provided for all vessels engaged in the fishery to document catches, effort, and fishing areas. Laboratory processing of fish samples in- cludes measurements of body length and depth, body weight, and gonad weight. Sex is determined, and scale, stomach, and gonad samples are preserved for analysis. Some highlights of research results to date (April 1967-February 1968) are: 1. Thread herring catches per unit of ef- fort (30-minute set with a 2-inch-mesh mono- filament gill net) in Gulf waters off St. Peters- burg Beach reached a peak in early summer and declined with falling water temperature in the fall. Heavy concentrations of fish (as shown by commercial fishing) off Fort Myers during fall and winter indicate a general southerly or possibly offshore movement when coastal waters are cooling. Schools of thread herring, however, do occur off St. Petersburg in winter (Butler, 1961). 2. Juvenile thread herring appeared in beach seine samples along Gulf beaches in the St. Petersburg area during summer and disappeared by fall, indicating an offshore movement of juveniles. 3. Thread herring had fully developed gonads at 5j to 6f inches fork length off St. Petersburg Beach in early April. Spent gonads, indicative of spawning, appeared by late May when water temperature was about 81° F. Gonad development indicates a spawn- ing peak in June. No gonads were ripe in July, The gonads of fish from commercial catches off Fort Myers during winter have been un- developed. 4. The ratio of males to females in the summer thread herring population off St. Pete
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