LOVE ET AL.; Llf^E HISTORY AND FISHERY OF CALIFORNIA SCORPIONFISH 



(Emlen and Oring 1977), in which fish migrate to, 

 and aggregate at a "traditional" spawning site for 

 brief (though undefined) periods. Reproduction is 

 polygamous and sexual selection is low. Thresher 

 (1984) speculated such behavior may be the primary 

 reproductive mode of larger pelagic spawning reef 

 fishes— such as snappers, jacks, and barracudas. 

 Smaller fishes would find a spawning migration dele- 

 terious, owing to a higher predation risk while 

 traveling. 



California scorpionfish do indeed migrate to "tra- 

 ditional" spawning areas and are pelagic spawners. 

 With 50% maturing at 17 cm, they are smaller than 

 the usual explosive breeding assemblage species 

 listed by Thresher (1984). However, it is likely that 

 mature California scorpionfish are not heavily 

 preyed upon (because of their toxin-carrying spines) 

 and thus may be an exception to the rule. 



The Dago Bank spawning site is, for the most 

 part, a sandy environment, usually inhabited by 

 relatively few fish. Spawning in a deep-water, rela- 

 tively depauperate area, the California scorpionfish 

 may avoid some of the egg predation expected in 

 the shallow reefs inhabited during fall-spring. More- 

 over, by spawning well above the substrata, newly 

 spawned eggs are kept away from benthos-dwelling 

 predators. Many coral reef fishes exhibit the same 

 behavior, which not only decreases egg predation 

 but also places the fertilized eggs into surface cur- 

 rents, increasing the chances of larval dispersal 

 (Thresher 1984). 



We do not know how many spawning sites exist 

 off southern California. Santa Monica Bay (Turner 

 et al. 1969) and Dana Point (Cross fn. 6) are likely 

 sites while Anacapa Island and the Coronado Islands 

 (M. Love, unpubl. data) might also be utilized. We 

 have no data on how many years these sites persist 

 as spawning areas. Judging from other species (such 

 as Clupea harengus—Cushing 1982), it is likely that 

 scorpionfish spawning grounds are probably of long 

 duration. 



For several reasons, this behavior is unusual 

 among fishes in southern California. First, only a 

 few species (notably kelp bass, Paralabrax clathra- 

 tus; barred sand bass, P. nebulifer; sargo, Aniso- 

 tremus davidsoni; kelp surfperch, BrachyistiiLS fre- 

 natus; senorita, Oxyjulis califomica; and sheephead, 

 Pimelometopon pulchrum, Feder et al. 1974) form 

 relatively long-term (to a few months) spawning ag- 

 gregations. It is noteworthy that, of these fishes, 

 all except the barred sandbass are midwater, active, 

 species particularly when compared with crevice- 

 dwelling scorpionfish. 



Second, few reef associated species move off reefs 



to spawn. Barred sand bass are one of the few ex- 

 ceptions. These form large spawning aggregations 

 over low relief or flat substrata within the Southern 

 California Bight (Turner et al. 1969). The vast ma- 

 jority of reef dwelling fish are relatively sedentary. 

 Many are either territorial or occupy home ranges. 

 Virtually all stay within the reef vicinity. For these 

 species, spawning takes place within their usual 

 habitats. 



Lastly, the California scorpionfish does not have 

 the morphology of a fish given to long movements. 

 Such adaptations can be seen most graphically 

 among the northeast Pacific rockfishes, genus 

 Sebastes. Sedentary, territorial species, such as the 

 gopher rockfish, 5. carnatus, and treefish, S. ser- 

 riceps, are very spiny, squat, and deep-bodied forms. 

 More active, midwater species, such as the yellow- 

 tail rockfish, S. Jlavidus, and boccacio, S. pauci- 

 spinis, are more streamlined, with reduced spines 

 (particularly about the head). This trend culminates 

 in the pelagic shortbelly rockfish, S. jordani, which 

 resembles a mackerel or sardine. In contrast, 

 California scorpionfish closely resemble the benthic 

 rockfish. Yet, the species seems to move about 

 considerably, even excluding movements to and 

 from spawning grounds. Tagging data from studies 

 of the California Department of Fish and Game 



show movements as much as 190 km (Hart- 

 mann^^) 



Food Habits 



We sampled 24 California scorpionfish (TL = 21.2- 

 32.5 cm) with food in their stomachs. Though we 

 captured many hundreds of scorpionfish throughout 

 the Southern California Bight, individuals taken in 

 water deeper than about 16 m regurgitated prey 

 during capture. The 24 individuals with prey repre- 

 sented 68.5% (24 of 35) of all scorpionfish taken in 

 water <16 m. 



We have graphically represented prey importance 

 (Fig. 10), using the Index of Relative Importance 

 (Pinkas et al. 1971). Crabs were the most important 

 food item. These were primarily juvenile Cancer an- 

 thonyi, but we also found a few Loxyrhynchus sp., 

 Randalia omata, and Pagurus sp. Fishes were sec- 

 ond in importance. Recognizable species were the 

 northern anchovy, Engraulis mordax, and the 

 spotted cusk-eel, Chilara taylori. Octopi, isopods, 

 shrimp (pumanly Alphaeus sp.), and small pebbles 

 made up the rest of the diet. 



i^A. R. Hartmann, California Department of Fish and Game, 

 Long Beach, CA 90802, pers. commun. June 1984. 



109 



