RICHARD K. STROUD 



Northwest and Alaska Fisheries Center 

 National Marine Fisheries Service. NOAA 

 7600 Sand Point Way NE., Seattle, WA 98115 

 Present address: Department of Veterinary Medicine 

 Oregon State University 

 Corvallis, OR 97331 



Clifford H. Fiscus 



HIROSHI KAJIMURA 



Northwest and Alaska Fisheries Center 

 National Marine Fisheries Service, NOAA 

 7600 Sand Point Way NE., Seattle. WA 98115 



SPAWN AND LARVAE OF THE PACIFIC 

 SANDFISH, TRICHODON TRICHODON 



Little is known about the biology of the Pacific 

 sandfish, Trichodon trie ho don, other than that the 

 adults are characteristic of inshore, sand-gravel 

 communities (Isakson et al. 1971); they occur from 

 San Francisco, Calif., to Kamchatka, USSR (Hart 

 1973); and they burrow into a sandy substrate 

 (Clemens and Wilby 1961). Clemens and Wilby 

 reported that a mature female taken on Long 

 Beach, Vancouver Island, Canada, extruded ma- 

 ture eggs (upon disturbance) in February. 



The first discovery of natural spawn of T. tricho- 

 don and subsequent rearing of larvae through 

 metamorphosis at the Vancouver Public 

 Aquarium has provided information about the re- 

 production and early life history of this species. In 

 addition to life history notes, this paper presents a 

 description of larvae of T. trichodon. 



Methods 



A portion of an egg mass was collected at lat. 

 48°56 ' N, long. 125°43 ' W, 16 km southeast of Long 

 Beach, Vancouver Island, on 12 June 1976 and 

 transported in a plastic bag with oxygen and sea- 

 water to the Vancouver Aquarium, where it was 

 incubated in an aerated aquarium with seawater 

 (25-29'L, 8°-13° C) provided at an inflow rate ex- 

 ceeding 100 tank volumes/d. The seawater tem- 

 perature changed seasonally with changes in av- 

 erage ambient seawater surface temperatures, so 

 that the salinity/temperature regime was com- 

 parable with that which the eggs would have en- 

 countered intertidally. The eggs were fixed in a 

 bag of nylon mesh in front of the inlet pipe. In 

 October, December, and January, embryos were 



excised from a few of the eggs to determine 

 whether development was continuing. About once 

 per month egg membranes were scrubbed with a 

 bottle brush to remove diatom growth. 



As they hatched the larvae were collected with a 

 beaker and transferred to a 1,000 1 rearing tank 

 (ca. 1 m depth x 1 m in diameter) with seawater 

 (25-271,, 10°-12° C) inflow at a rate exceeding one 

 tank volume per day and a light cycle of 14 h light 

 and 10 h dark, including simulated twilight 

 periods. Larvae were provided brine shrimp, Ar- 

 temia salina, nauplii daily in excess quantities. 

 Debris was siphoned from the tank bottom daily 

 and examined for dead fish larvae. Juveniles were 

 placed in a tank with a sand bottom and flow- 

 through seawater and were fed frozen euphausiids 

 and frozen brine shrimp. 



At various ages specimens were preserved in 3% 

 Formalin^ in seawater, with borax and lonol. 

 Freshly killed specimens were measured to the 

 nearest 0.5 mm standard length (SL), then mea- 

 sured again 1 yr after preservation, to determine 

 shrinkage. Line drawings, morphometric data, 

 and meristic characters were based on preserved 

 specimens. 



Life History Notes 



The egg mass was found in a surge channel on a 

 rocky shoreline between 0.6 and 1.0 m tide levels. 

 The mass was visually estimated to have about 

 1,000 eggs, was irregularly shaped, and adhered 

 firmly to the rock surface. 



Adults of this species are known to inhabit 

 sandy beaches, whereas the egg mass is suited 

 only to rocky substrate to which it can adhere. 

 Presuming an incubation period of about 1 yr as 

 discussed below, most plant substrates would be 

 too ephemeral for an egg deposition site and bed- 

 rock on sand beaches could be covered by seasonal 

 shifting of sand. Rocky shoreline removed from 

 sandy areas would therefore provide the most sta- 

 ble substrate for the adhesive eggs. The precise 

 location on the wall of a fully exposed surge chan- 

 nel might provide a refuge from egg predation as 

 well as high flow velocities for gas exchange. The 

 rocky intertidal area in which this egg mass oc- 

 curred is located 8 km from the nearest sandy 

 intertidal area. Thus, a limited spawning 

 movement along the shore must occur. 



^Reference to trade names does not imply endorsement by the 

 Vancouver Aquarium or by the National Marine Fisheries Ser- 

 vice, NOAA. 



FISHERY BULLETIN: VOL. 78. NO. 4, 1981. 



959 



