j V


FRm/S95 FAO Fieherie SynopoioNo.95 SASP - Prawn

SYNOPSIS O BIOLOGICAL DATA ON THE PRAWN Panda.lua ylatycoros Brandt, 1851

Exposé synoptique sur la biologlo de platyceros Brandt, 1551

Sinopsis sobro la biología dol Pandalus platyceros Brandt, 1851

preparad by

T.H. BUTLER Fisheries Research Board of Canada Biological Station Nanaimo, British Columbia, Canada - 1291 -

m/395P. platyosros j


Page No,


1,1 1

1.1,1Definition 1 1.1.2 Description 1

1,2 Nomenclature 1

1.2,1 Valid scientific names i 1.2,2 Synonyms 1

1.2.3 Standard oommon names, vernacular names 1.

1.3General variability 3

1.3,1 Subspeoifio fragmentation (races, varieties, hybrids) 3 1.3.2 Genetic data (chromosome number, protein specificity)


2.1 Delimitation of the total area of distribution and ecological characterization of this area 1

2,2 Differential distribution 1

2.2.1Areas occupied by eggs, larvae and other junior stages: annual variations in these patterns, and seasonal variations for stages persisting over two or more seasons

2.2.2Areas occupied by adult stages: seasonal and annual variations of these

2.3Behaviouristic and ecological determinants of the j'eneral limits of distribution and of the variations of theo limits and, of differential distribution*


3.1 Reproduotion i

3.1.1 Sexuality (hermaphroditism, heterosexuality, intersexuality) 1 3.1.2 Maturity (age and size) i 3.1.3Mating (monogamous, polygamous, promiscuous)* 3.1,4Fertilization (internal, external) * 3.1.5Fecundity i 3.1.6Spawning 1 3.1.7 Spawning grounds 1 3.1.8Egg: structure, size, hatching type, parasites, and predators i

3.2 Larval hietox7 i

3.2.1 A000unt of embryonio and juvenile life (prelarva, larva, postlarva, juvenile)

This synopsis has been prepared according to Outline Version No, 1. (H. Rosa Jr., FAO Fieh.Synops,, (I) Itev.l,1965). - 1292 -

ii FRin/S95P. platyoeros

Page No,

3,3 Adult history 3*5

3,3.1 Longevity 5 3.3.2 Hardiness S 3.3.3 Competitors 5 3.3.4 Predators 5 3.3,5Parasites and diseases 5 3.3.6 Greatest size 5

3,4Nutrition and growth 5

3,4.1 Feeding (time, place, manner, season) 5 3,4.2 Food (type, volume) 5 3.4.3 Relative and absolute growth patterns and ratee 5 3.4.4 Relation of growth to feeding, to other activities, and to environmental faotore *

3.5 Behaviour 6

3.5.1Migration and local movemente 6 3.5.2Schooling * 3,5.3Reproductive habits


4.1 Struoture

4.1.1 Sex ratio 4.1,2Age composition 4,1.3 Size composition

4.2 Size and density

4,2.1Average size 4,2.2 Changes in size 4,2,3 Average density 4,2,4 Changes in density

4,3 Natality and recruitmant 1

4.3.1 Natality * 4.3.2Natality rates

4,4Mortality, morbidity

4.4.1 Rates of mortality 4,4.2Factors or conditions affecting mortality 4,4,3Factors or conditions affecting morbidity 4.4,4Relation of morbidity to mortality rates

4.5 Dynamics of population 1

4.6 Relation of population to community nd ecosystem, biological production, etc.*


5.1 Fishing equipment i

5.1.1Fishing gear i 5,1,2Fishing boats i 1293 -

FRmJ. . lat oeroe iii

Page No0

5,2 Fishing areas 5t]. 5.2.1 General geographic distribution i 5.2.2 Geographioal rangos (latitudes, distances from coast, sto,) 1 5.2.3 Depth ranges 6 5,3 Fishing seasons 6 5.3.1 General pattern of fishing season 6 5.3.2 Duration of fishing season * 5.3,3Dates of beginning, peak and end of season * 5,3.4 Variation in time or duration of fishing season* 5.3.5 Factors affecting fishing season *

5.4Fishing operations and results 6 5,4.1 Effort and intensity 6 542 Seleotivit 6 5,4,3 Catches 6 5.5 Fisheries management and regulations 6 5,6 Fish farming, transplanting and other intervention *


* As no information was available to the author, these itom have been omitted from the text. - 1294 - 595 P. platycoro i IDENTIFY ii, Rostrum less than 1Y2 times as long as CarapaO 1,1Taxonom

Antennal conic very narrot:, dia--- l.,llDefinition tal half of blade narrouer thcm adjacent opino, P. opis Phylum ArtlLropoda Clase Cructacea Antennal scale of moderato width, Subclass Lalaoostraoa distal half of blade wider than Order Doonpoda adjacent spinet,P. Suborder Natantia Section Canden Spool! Superfamily Pandaloida Family Pandaljdae The holotype of P. platyceros, if still d.aius Leach 1814 extant, may be in the Zoological Museum at Species Pancialus platcsros Leningrad.Type looslityx "bei der Insel Brandt, 1851, Unalasohka" (.Unalaeka Island, Aleutian Is- 1.1,2Desoription lands, Alaska) (Brandt, 1851). Generic The speoles is illustrated in Fig. i. Pandalus Leach, 1814, Brewster's Edinburgh Encyclopaedia, 7:432.Gonder:maeculine. Type The following description of P, platy- species, by sionctypyr Pandaiue montagui Leach ceros is taken from Schmitt (1921). 1814. Body stout,Carapace covered wi'h The generic concept as used by Holthuis short pubesoenos,Rostrum 1Y2o 1 2/3 i:oo (1955) has been adopted.The following defin- length of carapace, provided ,,ith broad, entire, ition of the genus Pandalus is based on him laminar orest on each side; doroel spluen 14 'Iey to the Pandajidas', to 17, extending to middle of rOatrum, anorior 1 to 5 spines fixed and rest movablu; ucually Carpus of 2nd pereiopode consisting of a single spine near acute tip; venlral flied more than 3 jointe.No longitudinal carinne spines 7 or 8; anterior Y2 to 2/3 asoendiug, on the oarapaoo except the postrostral crest. tip above level of carapace,Antennal scalo Rostrum not movable.Eyes well developed, 4/5 to 7/8 length of carapace, oblong, distal cornea much wider than eyestalk.Third sezii- part of blade subtruncate, slightly exceeded liped without exopod.Laminar expansion of by spins.Right second persiopod reaches dimO- the inner border of the lechium of the let tal end of 3rd maxillipeds, carpuc crth 8 or 9 pair of pereiopods wanting or inconspicuous. aements; left pereiopod. 2/5 1engh of right, The first 4 perelopods with epipode.Arthro- oarpua with 2f or 28 segmente.Abdomen moro branche present at the bases of the first 4 1than 2 times length of oarapaooceooh, uot pereiopods,Posterior lobo of scaphognathite carinated,Colour of adults 1igh,en to rec1 acutely produced.Upper margin of rostrum dish brown, juveniles green or darh brota; with movable spines only. horizontal white striping on oarapace2 white spots on let and 5th abdominal segments, Nine species of the genus nda1uo occur along the west coast of 1Joh America0Five 1,2Nomenclature species, P, platyceros, P, danno S1speon, o teno1e Rathbun, gurn.r) Stispoon, 1,2,1Valid soientifio names and P, hypsinotue Brandt, appear to be olonoly ro!a sd, Pandalue platyoeroe Brandt, 1851, in: Middendorff, Relee N.U. Sibiriens, vol, 2 pt. The following key is based on Rathbun 1, p.123. (1904) and Schmitt (1921): 1,2,2Synonyms IDorsal spines on rostrum and carapace not reaohing behind middle of ocrnpaoo, Objective eynonymy ros No ne IIDorsal spines extending behind middle of oarapaoe Subjective synonymy i)Dorsal spines more than 15, P. hynsii- Pandalue pubesoentulue Dana1852, Crust. otus U,S,Explor.Rxped (1838-42), 13(15. 2)Dorsal spines leas than 15 1,2,3Stanthrd common names, vernaoular SLeOC i,Rostrum at least 1Y2 Umso as long as oarapao, P, In Alaska and Waehington the species is Fie. i carapacePanda].u8 length patyceos Brandt. 4 na. Dorsal and side views of female, - 1296 -

FRm/S95 P. p1atoeroe known ao the spot shrimp, or spot. The oommon name in British Columbia and California is the prawn.

1.3 General variability

1.3.1 Subepeoific fragmentation (races, varieties, hybride)

Subepeoiee or varieties have not been es- tablished for P. platyceros.

The species te distinot from its several oongeners and is reoognized by all special- its as a valid species. -1297 -

/S95P, platyoeroo 2,1

2 DISTRIBUTION 2.2 Differential distribution

2.1 Delimitation of total area of dis- 2.2.1 Areas occupied by eggs9 lar- tribution and ecological oharao- vae and other junior stages r terization of this area annual variations in these patterns, and seasonal varia- The prawn occurs in the North Pacific tiens for stages persisting Ocean, along the vest coast of North Amorioa over two or more seasons from Unalaska to San Diego; and in Asian wa- terse Hokkaido, Toyama Bay, Nagasaki, Korea, Prawns breed in relatively deep water Vladivostok. In terms of the FAO areas codo (73m, and deeper) in the auumn, Eggo nra (seo Hoithuim and Rosa,1965)it occurs in carried over the wintermont13sby he l'ancien parts of mea areas INE and IBE, and on the which appear to remain in %he breading arca coasts of land areas 211, 212, 220, 231, through hatching of larvae, 232, 444, 451 and710. The species lives in bays and inlets, on the continental shelf, Berkòley (1930) found the tiret and cocead and continental slope. It has a wide bathy- larval sbnges in deep untar near ho haÙita0$ metric range from4to487 a. adult prawns. The earlier larval stagoc say inhab.t the louer half ol' ho rater ColUwn, In generai, the area of distribution is Larvae, determned ac the 4th and 6th otegao, characterized br (i) relatively large contin- were collected by the same author from water of entai shelf, (2) low to high precipitation and 4to 6 s in depth. runoff, (3) relatively low to high surface Metamorphosis in early summer main- salinity,(4)surface temperatures 2°-20°C in 000iirs ly in shallow water, particularly in bays and the eastern Pacific with a seasonal range of shallow inlets, from the sublittoral to about lO°-25°C in the Sea of Japan, sur-' 3°-7°C; (5) m, The postlarval prawns remain in this tace currents changing with seasonal winds 55 zone for most of the first year of life, but and (6) basic organic productIon: medium to high, leave the sublittoral before the winter, 2,2,2 Areas occupied by adult et Bottom temperature and salinity values seasonal end annual variations for the species wore recorded by Butler(1964) o$ hao ast By the time of first maturity, in the 2ud T °C S yr, prawns have migrated to relatively deep water, Maximum 10,97 30.83 Evidence of annual variations in differen.. Minimum 7 61 26 42 tial distribution is not available0 - 1298 -

FRm/S95 P. platyosros rl

3 BIOMOMICS AND LIFE HISTORY There is no evidence that the prawn breeds more than once a year. Presumably relatively 3.1 Reproduotion few Vancouver Island female prawns breed more than once in their lives, 3,1,]. Sexuality (herrnaphroditism, heterosexuali.ty, intersexual- 3.1.7 Spawning grounds ity) The evidence is that prawns breed in their The species is hermaphroditic (Berkeley, normal adult habitat at depths greater than 1930), Each Individual matures and funotions 73 n, where the bottom is rocky. first as a male, then pasees through a transi-. tion or intersoxual phase to become a female, 3,1,8 Egg: structure, size, Primary or early maturing females which occur hatching type, parasites and in other pandalids (Allen, 1959), have not predators been reported. Apart from females bearing ex- ternal eggs, the sex of prawns may be deter- The egg structure has not been studied, mined by examining the endopodites of the first In southern British Columbia on 25 February 2 pleopods, In the male the endopodite of the 1964,138 "eyed" eggs from 23 ovigerous fe- 1ml; pleopod or organ of copulation is tapered, males, 33.5 to 41.4 mm carapace length had a with a slight "shoulder" or protrusion, and mean length and diameter of 2,0 msi andl,.5mm, has at its tip a series of small hooks or cm- respectively. There is no information avail- oinnuli; lower on this structure is a group of able on parasites of developing egcs, well-developed, stout spines, On the inner margin of the endopodite of the 2nd pleopod, 3.2 Larval history in addition to the appendix interna, is the appendix masculina which is distinctly longer 3.2.1Account of embryonic and than the former and is armed with about15 juvenile life (prelarva, thornlike sets.e. In the female, the endopodito larva, postlarva, juvenile) of the let pleopod is elongate and niblike, following atrophy of the tip with cincinnuli According to Butler (1964) the embryonic and development of the protrusion mentioned period lasts from 5 to 5Y2 mo with hatching in above as the new tip; the spines and the setae late March or early April, The eggs are cara proximal to them disappear, On the 2nd piso- ned on the first 4 pairs of pleopods, as in pod the appendix masculina is absent, having other carid.ean shrimps. The colour of the egg atrophied through intersexual moults. changes from a lsrk orange when freshly extru.- ì to brown at time of hatching, 3,1,2 Maturity (age and sise) Berkeley (1930), including the prawn with In southern British Columbia the species other pandalids studied in the laboratory, matures first as a male at about 1Y2 yr, hav- found that most larvae hatch at night, She ing a mean carapace length of about 28 mm. reported that the female moves the pleopodo Most individuals appear to romain as males for vigorously for about a minute to release from another year; the rest change sex and function 5to25larvae, while clinging to some object as females at 2Y2 yr when the mean carapace or while swimming freely, After release of length im about 33 mm, Those females which each batch, the female rests for 10 min or mature at 3Y2 yr have attained a carapace longer and then the procedure is continued length of about 38 mm (Butler, 1964), until all larvae are free, Hatching is fre- quently completed in one night but sometimes 3.1,5 Fecundity takes two or moro days,

Near Vancouver Island the relationship The let larval stage of the prawn was between fecundity and carapace length has been reared by Berkeley (1930), She collected let calculated, Egg counts from 21 females, 33,5 and 2nd stages and others, determined as 4th to 41,4 mm, ranged from 1,393 to 3,162; the and. 6th, from the plankton, The 4 known stae equation was: Log F 3,3967 log L - 2.0564 are illustrated in Fig. 2 and 3, and the oharao- ( number of eggs, L 's carapace length in ters are summarized in Table I, mm). Near Petersburg, Alaska, Hynes (1930) found an average count of 3,900 eggs, based The same author described a later stage, 2 on 5 individuals. orn long, undoubtedly postlarval, which has mainly adult characters except for the presence 3.1,6 Spawning of the ocellus, rudimentary development of the antennules, and the podobranchia on the 2nd The prawn breeds in the autumn. In maxilliped, small arthrobranchiae, and the lack southern British Columbia all females examined of secondary sex characters. around the end of October were ovigerous (Butler, 1964), -1299

, 2 FHm/S95 P. platyceros

Fig. 2 Pandalua platyoeros, first stage larva. (A) Entire larva, lateral view, (B) Dorsal view of oephalothorax and. appendages0 (C) Lateral expansion of carapace much onlar.d, (D) Antennule, (E) Antenna, (F) Mandjbles, (o)(R) First and. 2nd. maxillas respectively, (I)(J)(K) First, 2nd and 3rd maxilliped.s respectively,, (L)(M)(N) First, 2nd and 3rd pereiopod respectively. (o) Telson, (After Berkeley, 1930) - 1300 -

FRm/595 P. platyoero@ 3:3

Fig.3 Pandalus platyoeros Second, 4th and 6th (?) stage larvae. (A) Socona stage larva, lateral view, (B) Third pleopod of same, (C) Pelean of same, (D) Fourth stage larva, lateral view. (E) Second maxilla of same. (F) Third pleopod of same, (a) Telson and uropod of sano, (H) Sixth (?) stage larva, lateral view. (After Berkeley, 1930) - 1301

FRa S P. mt ceros


Larval development of tho prawn (based on Berkeley,1930)


1 8 mm long, brightly coloured, Lateral margine of carapace and posterior margins of abdominal segments expanded and clenticulated.Rostrum large, with9dorsal spines, Inner flagellum of antermulo with 3 simple setao, Scale of antenna with 6 plumoso setas and 19-20 simple setae on inner margin; 2 simple setas on outer margin, Eyes immobile, First maxilliped with bibbed epipodite; 2nd with simple9 tablike epipodite, Second peroio- pod with functional chela; maxillipeds and persiopods 1 - 3 bear exopodites bude of pleurobranohias at bases of pereiopods.Pleopode present as simple or bibbed bud-s. Telson with 16 setae,

2 lb mm long. Lateral margins of oarapaoe still expanded and serrated. Supraorbital spine present, rostrum with 15-16 dorsal spines, and 3-4 ventral spines, Eyes stalked Flagellum of antenna with 2 segments, Epimeral plates developing on abdominal eomites, Dentiolee on abdomen not as well developed an in first stage, Ploopode biramnous, Telson longer and with stouter seta than in first,

4 15mm long. Lateral expansions and serrations of carapace nearly disap- peared, Supraorbital spine present, rostrum bears about 17 strong dorsal- spines and 4 ventral spines. Antenna near adult, with segmented flagellum. Mastigobranchiae on 3rd maxilbiped and persiopods, Pleopods jointed, setose, and appendices internas present, IJropods separated, with rani well developed. Telson wider at tip, 6 pairs terminal and 2 pairs lateral setae.

6 16 rem long, Supraorbital spine absent, rostrum with 16 dorsal spines,5 ventral spines, Mandibles, maaillae, saxillipeds approaching adult form, Pereiopods have vestiges of exopoditos, otherwise all adult except 2nd, Arthrobranchiae present as buds on first4pereiopode, all pleurobranchias present, Pleopods well developed, - 1302 -

*,/595P. p1atyoiro 3:5

The smallest postlarval or juvenile pratrn 3.4Nutrition and growth collected, by Butler (1964) late in August 1961, had a carapace length of9.5mm (total length 3.4.1Peedin? (time, place, manner, about48mm); mean carapace length of others eeaon) in the same group, estimated at 1Y2 to 2 mo after metamorphosis, was14.4mm ;2 mo later Prawns have been observed feeding in aqua- this group showed a meen increment of almo2t ria day and night. Baited traps set during 4mm, It is no-t known at whioh length the ex- daylight hours and overnight will catch prawns, terna,l sex characters form. but no definite difference in catching rates has been demonstrated, 3.3Adult history 3.4.2 Food (type, volume) 3.3.1 Longevity In August 1927, Miss Berkeley examined Age estimates o± older prawns, as in other prawn stomachs collected at 2 localities near , leave much to be desired, The Vancouver, Her unpublished data are tabulated work of Butler (1964), however, indioats that as: relatively few prawns live longer than4 yr, Burrard Inlet Howe Sound 3.3,2 Hardiness _110m

Prawns appear to be very hardy, Fisher-. Total number of stomaohs 8 16 men keep them alive for as long as 10 days in Total with Crus-tacea 6 13 floating pens or sunken boxes under conditions Unidentified 6 12 of overorowding and variations of temperature Amphipod O 1 and salinity are likely. Total with Polychaeta 5 4 abellaridae, Pallasia sp 5 3 3.303 Competitors Polynoidae, possibly Lagisca sp O i The prawn is considered a benthio feeder, Nephthydidae, Nephthjys sp3 O so it is likely that some associated Maldanidao O 4 are competitors for food; for example, other Others decapod. crustaceans, pholithode forarninatus Fish scale O i (Stimpson), hispidas (Stimpson), Siliceous spon spioules O 6 and Chorilia longipes Dana. 3.4.3Relative and absolute growth 3.3,4Predators patterns and rates

Presumably a number of demersal, and even Butler (1964) found that the "oonversion pelagio, fishes are predators of the prawn, factor", i.e. the relative length of the cara- but no published record is known, Investiga- pace to total length (tip of rostrum to tip of tors have found unidentified "shrimps" in the telson), varied indireotly with size increase stomachs of several gadids (Hart, 1949) and and concomitant sex change as follows: dogfish (Chatwin and Forrostar, 1953). The lingood, Ophiodon elongatus Girard feeds on Sex Factor P. daTiae, a closely related commercial shrimp twilby, 1937), M 5,05 Transition 5,04 3.3,5 Parasites and diseases F 4076

There is no record of eptoaridean isopods Reoent work (Butler, MS) shows that th cia- parasitic on the prawn, crease in value of the conversion factor any be attributed to the rOstral length, After coz A male prawn, 32,5 mm oarapaoe length, change -takes place, the growth of the rostrum, infested with a rhizooephalan, Sylon sp, was relative to the carapace, is less than in the found near the queen Charlotte Islands on 20 male phase and the carapace accounts for a rela- June 1966, tively greater part of the tots], length,

3.3,6Greatest size Butler (1964) calculated the length-weight relationship cf the prawn as: The species is said to reach 10 in (254 mm) in total length in Alaskan waters (Barr, Log W 2.93148 log L -3.07787, 1964). The largont specimen measured from British Columbia was an ovigerous female,61.1 where W total weight in g, and L carapace min carapace and 253 mm tia1 length. length in mrn, 303

36 FRin/S5 P, platïoeros 3.5,3Reproductive habits Berkeley (1930) was the first to study growth of the species. By analysis of (total) Mating of the prawn has not been observed. length frequencies of speoimens sampled periodi- It is likely, however, that mating behaviour cally near Vancouver, she determined the growth is similar to that described by Needler (1931) pattern which is summarized as: for Pand.alum cianae. The female generally soulte at night and apparently mating and oviposition Age in Mean occur within 36 h after this moult. The male months Sex total length mm locates the nubile female through a kinesis reminiscent to that when the is near 4 14 (immature) 45 food, The first action of the male is an at- 12 14 loo tempt to run up the back of the female, but he 18 M 150 may be shaken off by the larger female, When 24 14 160 the male suoceeds in holding the female he as- 30 14 i8o annam a position with the anterior part of hie 36 Trans. 195 abdomen under the posterior part of her osphalo- 38 F 200 thorax; sometimes the female rolls over and the 42 F 220 two lie side by side, Copulation generally takes a minute or less, leaving the female ith On the basis of oarapaoe lengths obtained a loose mass of spermatozoa between the bnses near Vancouver Island, Butler (1964) plotted of the last2 pairs of peroiopods, Oviposi- the growth curve mhown in Fig.4. In Table II, tion is carried out while the female is on the mean carapace and total lengths, and mean total bottom, resting on the dactyli of the 3rd porlo- weights at age intervals through4years of pods and on the telson, The 4th and 5th pairs life are summarized. of pereiopods are bent under the body and are kept active in an "elbowing" motion.The plea- 3.5 Behaviour pode move gently and continuously, and the eggo pase from the oviduots in a steady stream be- 3.5.1Migration and local movements tween the pereiopods to the abdomen, becoming 3ttached to the anterior pleopods first,Ovi- The migration of young prawns from shallow position lasts about half an hour, but after- coastal waters during the f iret year of life is wards, the female may remain in position for well established (Berkeley, 1930; Butler, 1964), the same period before moving about normally, small prawns have been caught in miciwater trawla but there is no oLear evidenoe of diel migration. '3o4

PRm/395 P. platyoers 3*7


I II 1...j I I o2 4 6 8 IO 2 14 16 8 20 22 24 26 28 30 3234 36 38 40 42 44 46 48 50 AprJ A O D FAprJ A O C) FApr J A O D FAprJ A O D FAprJ AQIIn monthsandtimeofyear

Pig. 4 p1stfoeroe, Means and rangea of carapace lengtha according to age. - 1305 -

FFU S P. lat osros


Pandalus tycoros, Moan carapace and to-tal lengths, and bodr weights9 at intervals from 5 to 50 months of ago

ean carapaoe Mean total Mean total

Month (in months) Sex length ( ) length (mm) weighs (g)

Azgust n 14,4 73 2,1

Movamb r 7 N 18,3 92 4,2

April 12 M 21,2 107 6,4

August 17 M 26,7 135 12,7

November 19 N 27,7 140 14.2

Apzil 24 28,5 144 15,4

November 3]. M 32,9 166 23.4

November 31 F 33.2 158 24.1.

April 36 Trans 33,7 170 25.1

November 42 F 37,9 180 3505

June 50 F 42.1 200 48,3

M -Malos F Females - Males F -. Females -+ Trane. - 1306 -

FRm 5 P lot coros

4 POPULATION (spocx) Dahistrom (1963), fishing experimental trape near Monterey, California, in lato January, 4.1 Structure oalculaied the mean oarapaoe lengths of males, traneitionals, and females os37,0, 41,8,and 4.1,1Sex ratio 47.9tnj, reepeotively, Counts ofholo shriapa ranged from15.8to29.5per kg. A year later In a hermaphroditio animal uoh ao the Odomar (1964), fishing in the sorno region, pram, max ratio appearo to hayo little mean-P noted praotioally the same mean carapace lengths ing. Duo to natural and fishing mortality one and a similar rango of counts, would expect to find fetior of the older femaba in a population. 4.3Natalit' and reoruitrnent

4,1,2Age composition Recruitment to the trap fishery in south- orn British Columbia takes placo at about 1Y2 No sampling date. of commercial catche u yr. In the sano region younger prasma caught are available. Pramn caugh ii trape aini1a' in trawla are utiljoecL, to oommeroial gear near Vancouver Island 'ere composed of 4 and., at times including the O- 45 ynamios of populat&om group,5age groupu (Butler,l964) The do- minant age groups were 1+, 2+, and3+yr olds, it io assumed that Britsli Columbia praum stooku are exploited at a lou level, and there 4.1.3Size composition is no evidence that it is othort'iee in other parts of the range. As stated above, informaioa on commercial la baokin, Using experimental trap gear Butler (1964) found throughout ho year that the oarapaoe lengths of malee ranged from 13.0to38.8sim, traneitionals from28.2to 40,3 mm, and females from30.8to45,5 mm, - 1307 -

Rm/S95 P. platyoero 51

EXPLOITATION P. plat.yceros is caught incidentally in trawling operations for othor pandalids, 5.1 FishinR equipment Large prawns may be sorted from the catch and sold separately but the bulk is processed with 5,1,1Fishing gear otner smaller

The gear used specifically for oatobing 5.1.2 Fishing boats prawns is a small, single-chambered trap, also known as a "pot". Trap design varies from There is no vessel type designed speoifi- area to area because practically all fishermen oally and used exclusively for prawn trap fish- build their own trapa. The common basio type ing. The type operating in the fishery is a is oblong with a conical entrarnos ai eaoh end small oombination vessel, generally the salmon (Pig, 5). Invariably the entrances are made gill-netter (Fig.7)and, to a lesser extent of netting, but traps may be constructed of the troller, Those vessels are from9to 12 n different materials and dimensions vary. A in length. welded frame of iron rod is usually covered with netting or wire mesh (Fig, 6); and a The power drum on a gill-netter will haul wooden frame has sides covered with spaced prawn traps without any special modification, wooden laths or pieces of plywood. Oblong One man normally operates a prawn boat, and trapa vary in size from 61 cm z 30 orn i 30 cm stands in the stern cockpit to handle traps to 91 cmx 45 cmx 45 cm, when setting and hauling. The line may lead from the drum over a block attached to a gan- The prawn trap fished near Monterey, Cali- try, or over a roller on the taffrail, A foot fornia, has been described by Phillips (1931), control for the druze leaves the fisherman's This trap is between 1,2 and 1.5 m long, is 91 hands free, Bait is renewed after the trap is cm in diameter at one end, tapering in a curve unfastened, and then the catch is dumped, into to about 23 cm in diameter at the other end. a container, After emptying, the baited traps There is one conical entrance1 at the large are closed and stacked midships, ready for re- end, which extends for about 60 cm into the setting, trap to an opening of 152 mm in diameter. The trap is woven of rattan cano, with circular Vessels without power drums lead, the line reinforcing wire, through a block on a davit mounted midships and haul with a gypsy or warping head,, ooillng Recently experimental prawn trapa have the line by hand., Two men are required for been fished in California (Dablatrom, 1963; this operation. By either method a string of Odemar, 1964), in British Columbia (Butler, 40 traps may be hauled in 1 to lY2 h, Prawn 1963) and in Alaska (u.s. Bur,Comm.,Fish,,l966, boats will fish a total of from 50 to 200 1967), The main finding is that trapa having traps, Normally those vessels fish daily but sides covered with solid materials (e.g. sheet some are fitted with refrigeration and make metal or plastic) catch moro prawns than traps trips lasting from 10 to 14 clays, covered with net or screening. 5.2 Fishinj areas Prawn trapa are fishoci. ou the bottcm by means of a groundline. Each trap has a short 5.2.1 General geographic distribu- leader line, about 2 ra in length, which has a tion snap hook or clip at the end. io attach the trap to the groundline, Up to 40 trape may be put Table III summarizes known prawn f ish1n on a groundline, spaced9or 18 m apart. A areas. Evidently there is little, if anyr light anchor, or a small weight of concrete ox' prawn fishing in Alaskan regions other than scrap iron, is placed at each end of the ground- the southeastern area. Ronholt (1963) states line where the lighter buoy linea are attached, that P. platycoros was not caught west of Port In the past, treated manilla linos wore usad Dick tKenai Peninsula) by trawling in the but now polypropylene linos are used throughout course of exploratory cruises. the f ishery, Inflatable plastic buoys mark the position of the gear, but, where there is much 5.2.2 Geographic rangos (latitudes, boat traffic, fishermen may dispense with sur- distances from coast, etc.) face markers; they are able to grapple without difficulty the polypropylene groundline, which Latitudes (approximate) 58°N l36°W to in places is off the bottom,When wooden traps 47°N122°W plus 36°N 122°W, are new or have been ashore for a time they muet be weìghted separately so as to go to the The only prawn trap fishing ground not bottom satisfactorily, located in a coastal inlet or sound. is the region near Monterey, California, Traps are lifted once or twice daily, and the bait is renewed each time, Dogfish, shark, herring or scrap fish are satisfactory bait for prawns. A. 12" 24" lid supporting(hinges wires of wire) Sides covered by"Fastened to frame by wire No. 26 go. gaiv. iron rubber hOOK fixed tunnel entry 1/4" wire or steel ring ganging ring Diagrams of Prawn 2 1/2'Traps. inside diameter welded l/4"round mild steel IO" NefGaiv,Frames- round coverediron covered traps (net trap. 3/80 mild steel wetded.1i.nnels) Details tunnel entries Netting Fig0I 1/4" stretched mesh. 5 Nettingcovered,Diagrams trapsof prawn (net trape0tunanls)0 1Y4" stretched mesh. (i) Frames - roundNet covered 3/8" mild trap0 steel welded8 (B) Galvanized 1309

5Pp1atycero 5;3

Fig0 6 Frame trap, covered with ootton netting. Fig. 7 Trptoal Bxiti&i Columbia gillnettex. 1311

FRm/S95 Pplatyoeros 5i5


General geographie distribution

Alaska British Columbia Washington Californìa

Southeastern T5ainland Puget Sound Monterey

(Dixon En inlets, (Hood Canal) Peninsula

trance to (Smith Sound -

Cape Spencer Howe Sound)

Vancouver Island

(East and west

coast) -1312-

FRJn/595P. platyoeros

5.2.3Depth ranges shapes and dimensione, had prawns with averag- ing counts from26.6to28,8 (u.s.Bur.Comm, Alaska: 91to 110 m (Harry,1964). Bri- Fish.,1966). In a later report (U.s. Bur, tish Columbia:73 to 165 n(Butler,1964). Cosm,Fish.,1967),average counts of prawns Washington: unavailable, but probably within in traps with entrances of51and76mm (inside ranges above. California: around274 w (Phil- diameter) are compared; one kind of trap with lips, 1931). the smallerentrancesize caught prawns ave- raging37,2per kg and two trap types with the 5,3Fishin seasons larger entrences had prawns with separate ave- ra counts of24and 29.5 per kg. 5.3.1General pattern of fishing season 5.4,3 Catches

Trap fishing for the species takes place Recent British Columbia prawn catches, by almost entirely during the autumn and winter trap and trawl gear, are shown in Table IV, months, The reason for this pattern is that Also included in thie table, by way of compari- fishermen purane prawn fishing as an operation son, are trawl catohes of other pandalid spe- secondary to salmon gill-netting, trolling, or cies. other major fisheries, Total trap catches from other regions, In Butler's (1964) trap sampling data for Alaska (Chitwood,1964, 1965)and California the prawn (his Fig.16),there is an indica- (Greenliood and Mackett,1965, 1966),are given tion of an apparent decline in abundance, at in Table V. Statistics of the Puget Sound least of females, during summer months, Some fishery are shown in Table VI (R.E. Westley, British Columbia fishermen have reported thìs personal communication). disappearance which follows the hatohing of larvae in spring. 5,5Fisheries nana mont and regnlations 5,4Fishing operations and results Although no fishery for the species is being managed by measures based on the results 5.4.1 Effort and intensity of scientific research, there are regulations in existence which curtail fishing seasons and According to the Canada Department of restrict the design of traps. Fisheries the numbers of prawn traps owned and operated by British Columbia in reoont years Pertinent regulations are as follows: were: Number Alaska (Alaska Dep. Fish Gamo,1966). Year of traps Shrimp fishing (by definition of legal gear, includes traps and trawle) is prohibitod in 1960 1,240 the Petersburg-Wrangell area from15February 1961 1,341 to 1 May. 1962 2,582 1963 2,590 Washington (Pacif,mar,Fish Commn,,1965), 1964 2,620 Shrimp fishing, trapping and trawling, is pro- 1965 2,710 hibited in Puget Sound from 1 November to 31 March; fishing is restricted further in the British Columbia fishing effort for th Lopez Island area to30June, and in Skagit Bay epeoies, from1962to 1966,isshown in Table from 16 Jima to31August. IV as "trap days". These Canada Department of Fisheries statistics are collected by a sales California (Gates, 1965). North cf Point slip system, and a "trap day" is a day's opera- Conception;traps not to exceed183cm in tion by a prawn boat (without account of the greatest dimension and no opening from exterior number of traps hauled).The catch per day to interior may be greater than127mm in any has varied from42to57kg, dimension. 5.4.2 Selectivity From Point Conception south to the southern boundary of Ventura County; in waters not less The selectivity of oommeroial prawn traps than91m in depth.. No openings on traps, is undetermined. Trap experiments by bho U.S. through which prawns enter, shall exceed76mm Bureau of Commercial Fisheries in southeastern in greatest dimension. Alaska have shown that the sigo of prawns caught apparently depende on the size of trap entrances. In trars with circular entrances of51mm, inside dieter, average counts of whole prawns per kg ranged from32.8to38.9; while traps with largorentrances,of varioue 1313 -

FThn/S95P. platyoeros


British Columbia prawn catches, and trap fishing effort

Catoli (kg Fishing effort Year Trawl Trap (trap days)

1962 4,631 34,459 609 1963 8,036 30,917 581 1964 5,584 34,731 628 1965 4,631 18,659 405 1966 3,223 36,229 863


Prawn trap catches in kg, Alaska and California

Tear California Alaska

1962 315 1963 3,834 386 1964 2,622 2,461

1965 316


Prawn catchas in kg, trap and trawl, Pugot Sound, Washington

1962 7,911 499 913 1963 12,347 2,719 1,135 1964 25,652 1,516 1,366 1965 24,305 507 906 1966 18,740 229 88 -. 1314 -

FIbn/S9'P. o].a_tyoros 6t1


Alaska Department of Fish and Game, Regulations of the Alaska Board of Fish and Game for 1966 oommeroial fishing in Alaska, Juneau, 123 p.

Allen, J.A., On the biology of Pandalue borealis Kríyer, with referenoe to a population off the 1959 Northumberland coast. J.mar.biol.Ass.U.K., 38(l)l89-22O

Barr, L., Characteristics of the commercial shrimp landings at Wrangell, Alaska. Rep.U.S. 1964 Commnr Fish., MS Report (MR64-4); li p.

Berkley, A.A., The post-embryonic development of the common panctalids of British Columbia. 1930 .J.Fish.Res.Bd Can., 2l(6)l403-52. Issued also ast Contr.Can.Biol.Fioh., 6(6), 79- 163

Brandt, J.Y., Ki'ebse. In Dr. A. Th. von Middendorff's Reise in den ussereten Norden und 1851 Osten Sibiriens. 2. Zoologie, I.

Butler, P.R., An improved prawn trap. Circ,biol.Stn, Nanaimo, (67)t7 p. 1963

Growth, reproduction, and distribution of pandalid shrimps in British Columbia, 1964 J.Fish.Res.Bd Can., 21(6)z1403-52

Relativo growth of the rostrum in sev*ra1 pandalid species. MS

Chatwin, B.M, and B.C. Forrester, Feeding habitsof dogfish (Sczualus suckleyi (Oirard)). Frog, 1953 Rep,Pacif.Cst Stns (95)x 35-8

Chitwood P.L, 1963 Alaska commercial, fisheriesontoh and production statistics. Statist. 1964 Leaf 1.Alaska Dep.Fish Game, (7):26 p.

1964Alaska commercial fisheries catch and production statistics. Statist.Leafl. 1965 Á1ska Dep.Fish Game, (9)28 p.

Dahistrom, W., Cruise report 63-A-1, prawn-shrimp. California Department of Fish and Gaine 1963 Marine Resouroes Operations, 3p. (mimeo)

Dana, J.D., Crustacea. In United States exploring expedition during the years 1838, 1839, l85 1840, 1841, l2, under the command of Charles Wilkes, U.S.N. Philadelphia, Pa., vol.13

Gates, D.H., Digest of 1965-67 commercial f ih laws. California Department of Fish and Game 1965 Resources Agonoy, 31 p. Greenb.00d, E.C, and D.J. Mackett, The California marine fish catch for 1964. Calif.Fish Game, 1965 (132):45 p.

Statistioal report of fresh, canned, cured and manufactured fishery products for 1966 1965. Ciro.Dep.Fish Game Calif., (40).15 p.

Harry, G,Y., The shrimp fIshery of Alaska. Proo.Gulf Caribb.Fish.Inst., l664-7l 1964

Hart, J.L., Food of fish of the cod family. Prog.Rep.Pacif.Cet Stne, (79):35-6 1949 Holthuis, L.B., The recant genera of caridean and stenopodidean shrimps (Class Crustoosa, Order 1955 Deoapoda, Superseotion Natantia) with keys for their determination. Zool.Verh.,Leiden, 26,157 p.

Holtbuis, L.B. and H. RosaJr., List of species of shrimps and prawns of economic value. Q 1965 teoh.Pap.,(525*21p. 1315 -

622 FRrnJS95 P. platyceros Hynes, F.W., Shrimp fishery of southeast Alaska. Re,U.S,Commnr Fish., 1929 (Appendixl):18 Po 1930 Needler, A.B., Mating and oviposition in Pandalus danae. Can.Fld Nat.,45(5)l07-8 1931 Odemar, M., Cruise report64-A--1,prawn, California Department of Fish and Gamo Marino Re- 1964 souroes Operations,2 p. Pacific marinefieheries commission,Data seriesx crab and shrimp section,139 p. 1965

Philipp., J.B., Prawn fishery started at Monterey, Calif .Fish Game,l7(2)t159-62 1931

Rathbun, M.J., Decapod crustaceans of the northwest coast of North America,In Crustaoeans, 1904 Harriman Alaska Expedition,1O3-211. Reprinted1910, Publs,Smithson,Instn, (1997)zl-337

Ronholt, L.L., Distribution and relative abundance of commercially important pandalid shrimps 1963 in the northeastern Pacific Ocean, Spec.scient,Rep,U.S, Fish Wildl.Serv,,(449)828 p. Schmitt, M,L., The marine decapod Crustacea of California, Univ.Calif.Publs Zool,,(23)8470 p. 1921 United States Bureau cf Commercial Fisheries, Cruise report, exp]oratory fishing and gear re- 1966 search cruise66-1M/V LITTLE LADY, April 18-June13, 1966.4p,(mimeo)

Cruise report, Alaska exploratory cruise66-4,M/V JOHN R, MANNING, October 31-. 1967 Deoember16, 1966. 5 po(mimso) Wilby, G.V, Thling cod, Ophiodon elongatus Girard. Bull,blol,Bd Can,54x24 p, 1937