SHERIDAN ET AL.: RECAPTURE PATTERNS OF TAGGED PENAEID SHRIMP 



female shrimp exhibited similar recapture patterns; 

 and 3) recaptures after Tamaulipas releases ex- 

 hibited strong southward directionality and weak 

 westerly to northerly movement compared with 

 recaptures after Texas releases. 



Recapture depth was significantly influenced by 

 the main effects of species and state, but no inter- 

 action terms were significant (Table 7). Although 

 all shrimp were released at 18 m depths, mean 

 recapture depths of brown shrimp were greater than 

 those for pink shrimp (21.5-24.0 m versus 19.6- 

 21.5 m, respectively). Within each species, shrimp 

 released off Tamaulipas moved to deeper waters 

 than did shrimp released off Texas, and within each 

 state brown shrimp moved to significantly deeper 

 waters than pink shrimp. Most recaptures were 

 made within 16-20 m depths, a trend that was 

 stronger for pink shrimp than for brown shrimp 

 (Fig. 6). Brown shrimp were more frequently recap- 

 tured in 21-25 m and 26-30 m waters than were 

 pink shrimp. 



Commercial Fishing Patterns 



A total of 57,511 hours of fishing effort was re- 

 corded through interviews of fishermen landing at 

 Tampico during the survey period, with resultant 

 landings of 459.4 t of exportable shrimp tails. An 

 additional 262.7 t (36% of total catch) of "pacotilla" 

 or undersized, non-exportable shrimp taOs were also 

 landed (Castro''). Primary fishing areas were lat. 

 22°-23°N and 24°-25°N where Tamaulipas effort 

 was concentrated off river mouths or lagoon passes 

 (Fig. 7). 



Interviews of seafood processors and of vessels 



landing in U.S. ports after fishing off Texas during 

 1 June-31 August 1986 indicated a total fishing ef- 

 fort of 432,175 hours with landings of 6,479 t of 

 shrimp tails (NMFS, unpubl. data). Actual inter- 

 views of fishermen comprised 239,006 hours and 

 3,614 t of those totals. Logbooks kept by 47 Texas 

 shrimp vessels (a subset of interviews) recorded 

 13,501 hours and 190 t; thus the detailed logbook 

 data represented 3.1% of the total effort and 2.9% 

 of the total landings from Texas waters. Logbook 

 data were used to apportion total fishing effort off 

 Texas into grids. Texas effort was more diffuse and 

 was not clustered around river mouths or estuary 

 passes as it was off Tamaulipas (Fig. 8). 



Both fisheries operated in 1-82 m waters, of which 

 Texas has approximately 2.3 times the continental 

 shelf area as does Tamaulipas (U.S. Department of 

 Commerce, NOS Chart 411). Comparison of the 

 depth distributions of fishing effort between Ameri- 

 can and Mexican fleets (illustrated in Figure 9) in- 

 dicated that American fishermen expended signif- 

 icantly more effort in shallower waters than did 

 Mexican fishermen (mean fishing depths were 33.8 

 m and 35.1 m, respectively; (-test, P = 0.009). Over- 

 all catch rates were higher in Texas waters (6,479 

 t/432,175h = 15.0 kg/h) than in Tamaulipas waters 

 (722 t/57,511 h = 12.6 kg/h). Data collected concern- 

 ing fishing gear indicated that vessels in both fleets 

 generally employed four 12 m nets (mesh size data 

 were unavailable). 



^Castro M., R. G. Informe de actividades del programa MEX- 

 US Golfo, grupo camaron Mexico. Programa MEX-US Golfo 1986. 

 Unpubl. manuscr., 18 p. Institute Nacional de la Pesca, Centre 

 Regional de Investigaciones Pesqueras, Tampico, Tamaulipas, 

 Mexico. 



Table 7— Recapture depth for brown shrimp and pink shrimp released in 18 m waters. A. 

 Three-factor, model I ANOVA using log (x -i- 1) - transformed data. B. Mean recapture 

 depths. Underlined means are not significantly different (Fisher's LSD, a = 0.05). B = 

 brown shrimp, P = pink shrimp, F = female, M = male, Ta = Tamaulipas, Tx = Texas. 



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