FISHERY BULLETIN: VOL. 84, NO. 3 



material already present in that segment is isolated 

 from what might otherwise be a continuous column 

 of material. Both potentially produce gaps or 

 "clumping" of intestinal contents. Collection of data 

 affected by intestinal displacements should also in- 

 corporate increased sampling so that specimens with 

 herniations or intussusceptions can be eliminated 

 from the data set without a significant loss of 

 information. 



Survivorship: Experimental Design 

 and Fishery Management 



Our data show that experimental studies of sur- 

 vivorship and the physiological responses of sponge- 

 coral reef fishes following capture and release should 

 stratify their designs by gear. Traps and longlines 

 should be considered in future studies because of the 

 gear-specific vertical haulback rates and other stress 

 factors. Additional considerations are capture depth 

 (Gotshall 1964; Moe 1966, 1969; Moseley 1966; 

 Bradley and Bryan 1975; Grimes et al. 1983), preda- 

 tion on injured and disoriented fishes (Parker et al. 

 1959, 1963; Randall 1960; Topp 1963; Gotshall 1964; 

 Fable 1980), crowding and abrasion in the gear 

 (Pawson and Lockwood 1980), degree of gut full- 

 ness (related to stress from diverted blood supply; 

 Beamish 1966), physiological state related to long- 

 term feeding/activity cycles (Parker et al. 1959), 

 water column temperature structure, currents, and 

 turbidity. Many of the factors covary with depth and 

 fluctuate seasonally. 



The anatomical derangements investigated in the 

 present study are severe trauma. Oral and cloacal 

 protrusions would very likely cause high rates of 

 mortality in subsequently released fishes. Obstruc- 

 tion of the gastrointestinal tract would normally be 

 serious and interference with the blood supply to the 

 gastric and intestinal walls would lead to severe cir- 

 culatory impairment. Gotshall (1964) has shown that 

 returns from tagged blue rockfish, Sebastes mys- 

 tinus requiring stomach replacement and swim- 

 bladder deflation were less than half those from fish 

 requiring only swim-bladder deflation. These fish en- 

 dured everted stomachs for only a few minutes. 

 Topp (1963) has noted that the everted stomachs of 

 Lutjanus snappers are frequently perforated by the 

 fish's teeth. The effects of such injuries on survival 

 require further study. 



Expansion of the swim bladder in specimens which 

 do not experience gut protrusions likely induces in- 

 ternal damage undetected by external examination. 

 Aquarists commonly use swim-bladder deflation 

 techniques to increase survivorship of specimens suf- 



fering from decompression symptoms (D. Miller 6 ). 

 Gotshall (1964) increased tag returns of blue rock- 

 fish by deflating expanded swim bladders of speci- 

 mens collected as deep as 90 m. The technique also 

 reduces the effects of exopthalmia (protruding eyes 

 produced by expansion of gas into the cranial region) 

 on blue rockfish (Gotshall 1964), vermilion snapper, 

 big eye (Priacanthus arenatus), and short bigeye (D. 

 Miller fn. 6). 



Although tissue emphysema per se may not be 

 lethal, swim-bladder rupture probably is for some 

 species. Jones (1949) reported 90% mortality of 600 

 perches, Percafluviatilis, with swim bladders rup- 

 tured while being raised rapidly from 13.7 m. Topp 

 (1963) speculated that survivorship of sponge-coral 

 reef fishes with ruptured swim bladders is very low. 

 However, R. O. Parker 7 has observed healing of rup- 

 tured swim bladders in black sea bass. Further ex- 

 perimentation is needed to determine the effects of 

 swim-bladder rupture on a species-specific basis. 



It is likely that survivorship following release 

 varies with depth due to hydrostatic factors alone. 

 Regression of trawl-caught red snapper stomach 

 eversion proportions on capture depth (values from 

 the literature) explains 80% of the variance in the 

 observed data (Fig. L4; r = 0.90, df = 5, P < 0.01). 

 Inclusion of our trawl-caught red snapper data 

 rendered the relationship nonsignificant (Fig. L4; 

 r = 0.70, df = 6, P < 0.05). A similar plot of angling- 

 caught red snapper data from the literature was not 

 significant (Fig. IB; r = 0.58; df = 5; 0.10 < P < 

 0.05), possibly because of the differences in the sizes 

 of red snappers hooked with respect to depth (see 

 Figure 1 citations) and resultant differences in the 

 rates of ascent, or ontogenetic differences in relative 

 swim-bladder volume. Note that increased depth 

 eventually outweighs any real effect of the size of 

 the fish and tenacity of its struggle against the 

 angling gear, or anatomical variation, rendering the 

 overall relationship positive albeit nonlinear. The 

 above data (Fig. LA, B) also indicate that red snap- 

 pers caught with any gear over bottoms <30 m deep 

 do not suffer significant trauma. Similarly, depths 

 < 20 m introduced no difficulties to a food habits 

 study of this species (Moseley 1966). 



Clearly, regulations which diminish removal of 

 fishes (e.g., gear/method restrictions, area/time 

 closures) will be more effective over a larger depth 



6 D. M. Miller, Curator, University of Georgia Marine Education 

 Center, POB 13687, Savannah, GA 31416, pers. commun. 

 November 1984. 



7 R. O. Parker, National Marine Fisheries Service, Southeast 

 Fisheries Center, Beaufort Laboratory, POB 500, Beaufort, NC 

 28516, pers. commun. October 1984. 



702 



