DESCRIPTION OF LARVAE OF THE HUMPY SHRIMP, 



PANDALUS GONIURUS, REARED IN SITU 



IN KACHEMAK BAY, ALASKA 



Evan Haynes^ 



ABSTRACT 



Except for Stage I, identification of larval stages of Pandalus goniurus has not been verified by 

 rearing the larvae from known parentage. Larvae of P. goniurus were reared in situ in Kachemak Bay, 

 Alaska, from the first zoea (Stage I) through the first juvenile stage (Stage VII). Each of the seven stages 

 is described and illustrated. The descriptions are compared with descriptions of larval stages of P. 

 goniurus given by other authors. 



Studies on the early life history of pandalid 

 shrimp in Alaskan waters were begun in 1972 by 

 the National Marine Fisheries Service with the 

 initial objective of describing pandalid shrimp 

 larvae reared in the laboratory from known par- 

 entage. I have reported on larvae of coonstripe 

 shrimp, Pandalus hypsinotus Brandt, reared in 

 the laboratory (Haynes 1976). In the present re- 

 port I describe and illustrate larvae of humpy 

 shrimp, P. goniurus Stimpson, reared in situ in 

 Kachemak Bay, Alaska. A third report will de- 

 scribe larvae of pink shrimp, P. borealis Krdyer, 

 and compare the larvae of P. borealis with larvae 

 of other local pandalid species, including P. 

 goniurus. 



MATERIALS AND METHODS 



The laboratory technique used successfully for 

 rearing larvae of P. hypsinotus (Haynes 1976) 

 proved unsuitable for rearing P. goniurus beyond 

 Stage II. Beginning with Stage III, molting fre- 

 quency and number of larval stages of P. goniurus 

 reared in the laboratory were inconsistent, mor- 

 tality was high, and the larvae of a given stage 

 were not always morphologically identical. Rear- 

 ing P. goniurus in situ reduced mortalities and 

 yielded larvae essentially identical morphologi- 

 cally within each stage. 



Larvae were reared in situ from the first zoea 

 (Stage I) through the megalopa and first juvenile 

 (Stages VI and VII) in the following manner. Stage 



'Northwest and Alaska Fisheries Center Auke Bay Labora- 

 tory, National Marine Fisheries Service, NOAA, P.O. Box 155, 

 Auke Bay, AK 99821. 



I zoeae of known parentage were obtained using 

 the laboratory technique described by Haynes 

 ( 1976). The Stage I zoeae were then transported to 

 sea and placed in 500-ml flasks containing seawa- 

 ter of about 35%o salinity and 4°C obtained from 

 about 6 m depth with a plastic hand pump and 

 hose. Subsurface seawater was used to avoid the 

 lower salinity (about 28%o) of surface waters de- 

 rived from local runoff which, as I had found dur- 

 ing previous rearing studies, adversely affects 

 larval development by resulting in delayed molt- 

 ing and variable numbers of stages. One larva was 

 placed in each flask. The mouths of the flasks were 

 then covered with nylon screening of #0 mesh 

 (0.571 mm); the flasks were placed in holding con- 

 tainers and suspended upright at 15-20 m depth in 

 water about 40 m deep. The #0 mesh size allowed 

 plankton to collect in the flasks for food but pre- 

 vented the larvae from escaping. Each flask was 

 numbered and a record kept of the molting history 

 of each larva in each flask. Flasks were checked at 

 least every other day for cast skins and refilled 

 with fresh subsurface seawater. When a larva 

 molted, the cast skin was removed from the flask 

 with a large-bore pipette and preserved in 5% 

 formaldehyde for subsequent examination ashore. 

 Identification of larval sequence and stage was 

 verified using larvae obtained from plankton with 

 a net of #0 mesh towed near the bottom at about 2 

 kn in water 60 m deep. The plankton sample was 

 immediately placed in a glass receptacle contain- 

 ing several liters of subsurface seawater. Stage I 

 zoeae of P. goniurus were removed from the glass 

 receptacle using a large-bore pipette, placed in 

 500-ml flasks, one zoea to a flask, and reared to 



Manuscript accepted Julv 1977. 



FISHERY BULLETIN: VOL. 76, NO. 1, 1978. 



235- 



