DESCRIPTION OF LARVAE OF THE NORTHERN SHRIMP, 

 PANDALUS BOREALIS, REARED IN SITU IN KACHEMAK BAY. ALASKA 



Evan Haynes' 



ABSTRACT 



Northern shrimp. Panda! us borealis. were reared in situ in Kachemak Bay. Alaska, from Stage I (first 

 zoeali through Stage VIII (second juvenile). Each of the six larval stages and first juvenile stage is 

 described and illustrated, and a bnef description is given for the second juvenile stage. Apparently 

 larvae of P borealis in Alaska waters have at least one less stage than larvae of P. borealis in either 

 British Columbia. Greenland, or Japan waters. Of the known larvae of the North Pacific Ocean, larvae 

 of P- borealis are most similar morphologically to larvae of P goniurus but are separable from them by 

 being slightly larger in size and, in zoeal Stages I-III, by bearing more setae on certain appendages, 

 particularly the antennal scale and certain mouth parts. From Stage IV to megalopa, the rostrum of P. 

 borealis has more dorsal teeth, the second pereopods are more developed, and the pleopods are fringed 

 with more setae than for larvae ofP, goniurus -The criterion of the lack of an outer seta on the maxillule 

 for distinguishing zoeae oi Pandalus from certain other Candea is shown to be invalid 



In 1972 the National Marine Fisheries Service 

 began studies on the early life history of pandalid 

 shrimp in Alaska waters with the initial objective 

 of describing in detail laboratory-reared larvae of 

 each pandalid species previously unverified. Two 

 previous reports have described larvae of Pan- 

 dalus hypsinotus Brandt reared in the laboratory 

 (Haynes 1976) and P. goniurus Stimpson reared in 

 situ in Kachemak Bay, Alaska (Haynes 1978). 

 This report describes and illustrates each of the six 

 larval stages and the first juvenile stage of north- 

 ern shrimp, P. borealis KrOyer, and compares the 

 stages obtained from rearing in situ with descrip- 

 tions of pandalid shrimp larvae given by other 

 authors. A brief description of the second juvenile 

 stage is included. 



MATERIALS AND METHODS 



Rearing techniques were identical in all re- 

 spects to those described in an earlier report on P. 

 goniurus (Haynes 1978). Briefly, the technique 

 consists of obtaining Stage I larvae of known 

 parentage in the laboratory, then rearing the lar- 

 vae in flasks submerged at sea. Larvae from 

 plankton were also reared in flasks at sea in an 

 identical manner beginning with Stage I. Larvae 

 reared in flasks were compared with larvae from 



'Northwest and Alaska Fisheries Center Auke Bay Laborato- 

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

 Auke Bay. AK 99821. 



plankton for verification of sequence of stage and 

 larval morphology. 



Because the paired appendages of the larvae are 

 symmetrical, only one member (the left) is figured. 

 An exception is the mandibles which are drawn in 

 pairs. Orientation of surface of appendages in the 

 figures is given in the figure legends. The figures of 

 the appendages are in part schematic and repre- 

 sent typical setal counts. Variability in setation or 

 segmentation of paired appendages, such as the 

 difference in number of carpal joints between the 

 left and right second pereopods in the megalopa, is 

 mentioned in the text. Carapace length refers to 

 the straight-line distance from posterior margin of 

 orbit to middorsal posterior margin of carapace. 

 Total body length refers to the distance from tip of 

 rostrum to posterior margin of telson, not includ- 

 ing telson spines. Terminology, methods of 

 measuring, techniques of illustration, and 

 nomenclature of gills and appendages follow 

 Haynes (1976). Comparison of larvae from 

 plankton with cast skins from flasks was facili- 

 tated by first clearing the larvae in W7c KOH. For 

 clarity, setules on setae are usually omitted but 

 spinulose setae are snown. 



STAGE I ZOEA 



Mean total length of Stage I (Figure lA) 6.7 mm 

 (range 6.5-7.3 mm; 25 specimens). Live specimens 

 characterized by orange color; conspicuous 

 chromatophores throughout cephalothorax re- 



Manuscript accepted July 1978 



FISHERY BULLETIN VOL 77. NO 1.1979 



157 



