LARVAL DEVELOPMENT OF LABORATORY-REARED 

 ROSYLIP SCULPIN, ASCELICHTHYS RHODORUS (COTTIDAE) 



Ann C. Matarese 1 and Jeffrey B. Marliave 2 



ABSTRACT 



Larvae which hatched from egg masses collected at southwest Vancouver Island, Canada, were 

 identified as Ascelichthys rhodorus and were successfully reared through transformation. A devel- 

 opmental series from yolk-sac larvae through newly settled juveniles (5.9-17.6 mm SL) is described 

 and illustrated. Larvae hatch at approximately 6.0 mm SL and the yolk is absorbed by 6.5 mm SL. 

 Notochord flexion begins between approximately 8.8 and 9.0 mm SL and is usually completed by 

 11.0 mm SL. Transformation to the juvenile stage begins between 12.0 and 13.0 mm SLand is com- 

 plete in most of our larger specimens (15.0-16.0 mm SL). 



Ascelichthys rhodorus larvae possess the following distinguishing characters: 1) pigment patterns 

 along the ventral body and gut, 2) a pointed snout and moderately slender body as compared to other 

 cottids, and 3) four prominent preopercular spines. A series of larvae is examined for meristic struc- 

 tures, including fin ray, vertebral and caudal development, and sequence of bone ossification. All 

 structures except the caudal complex are ossified in our largest specimen ( 17.6 mm SL). Head and 

 preopercular spination is discussed. 



Minimum egg incubation time was 24 days (10°C); the minimum spawning period was 25 days. 

 Larvae were examined for swimming behavior; older larvae maintained a relatively high speed 

 schooling behavior throughout the planktonic phase. Settlement of juveniles started at 55-60 days, 

 with ambivalence over reentry to the plankton until about 90 days, when settlement became perma- 

 nent. 



The rosylip sculpin, Ascelichthys rhodorus, is a 

 small (11-15 cm) intertidal and subtidal cottid 

 species distinguished by smooth skin, a low spin- 

 ous dorsal fin, the absence of pelvic fins, and a 

 single hooked preopercular spine (Hart 1973). 

 Little is known of its biology and development or 

 its relationships within the family Cottidae 

 (Howe and Richardson 1978 3 ). The geographic 

 range of A. rhodorus extends from Moss Beach, 

 Calif., northward to Sitka, Alaska (Miller and 

 Lea 1972), and localized populations are com- 

 monly found throughout this range (Howe and 

 Richardson footnote 3). 



We provide here the first published descrip- 

 tion of the larvae of A. rhodorus with notes on the 

 development and behavior of the species in the 

 aquarium environment. 



'Northwest and Alaska Fisheries Center Seattle Labora- 

 tory, National Marine Fisheries Service, NOAA, 2725 Mont- 

 lake Boulevard East, Seattle, WA 98112. 



2 Vancouver Public Aquarium, P.O. Box 3232, Vancouver, 

 B.C. V68 3X8 Canada. 



3 Howe, K., and S. L. Richardson. 1978. Taxonomic re- 

 view and meristic variation in marine sculpins (Osteichthys: 

 Cottidae) of the northeast Pacific Ocean. Final Rep., NOAA 

 NMFS Contract No. 03-78-MO2-120. 1 January 1978 to 30 Sep- 

 tember 1978, Northwest and Alaska Fisheries Center, Na- 

 tional Marine Fisheries Service, NOAA, 2725 Montlake Blvd. 

 East, Seattle, WA 98112. Unpubl. rep. 



Manuscript accepted November 1981. 

 FISHERY BULLETIN: VOL. 80, NO. 2. 1982. 



MATERIALS AND METHODS 



Egg Collection and Laboratory Rearing 



On 23 March 1979, nine unidentified egg 

 masses were collected from under boulders on a 

 cobble beach, at the 0.9 m tide level, at Jordan 

 River (southwest Vancouver Island, Canada; lat. 

 48°25'20"N, long. 124°03'30"W). The egg masses 

 were incubated in flowing seawater of about 

 10°C and 27'/.. salinity at the Vancouver Public 

 Aquarium. Only three tanks were available for 

 rearing larvae, so some larvae that hatched on 

 different dates were mixed. Rearing tanks were 

 of 1,000 1 volume, with inflow rates of over 1 tank 

 volume/day. Newly hatched Artemia salinn 

 nauplii were fed in excess numbers to larvae 

 once daily. Larvae were killed and preserved (3% 

 Formalin 4 with sodium borate buffered sea- 

 water of 157.. salinity) at weekly intervals until 

 settlement from the planktonic stage started at 

 55-60 d. All preserved specimens were from two 

 rearing tanks, one with a single sibling group 

 and the other with a mixture of larvae from two 

 separate hatching dates (Table 1). Surviving 



4 References to trade names do not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



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