SCIENTIFIC COUNCIL MEETING - JUNE Results From Bottom Trawl Survey of Flemish Cap in July 1989

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1 OT TO BE CITED WITHOUT PRIOR REFERECE TO THE AOTHORIS) orthwest Atlantic Fisheries Organization Serial o AFO SCR Doc. 90/68 SCIETIFIC COUCIL MEETIG - JUE 1990 Results From Bottom Trawl Survey of Flemish Cap in July 1989 by A. Vazquez Instituto r de Investigaciones Marinas Muelle de Bouzas, Vigo, Spain A fishing survey of Flemish Cap was carried out in July 1989 on board the French R/V CRYOS to estimate cod stock abundance, redfish and American plaice. The survey was conducted in the same way as the 1988 one (Vazquez, 1989); like that it had a bottom trawl stratified random design following AFO specifications (Doubleday, 1981). A total of 129 bottom trawls were made up to a depth of 720 meters (400 f.). A synoptic sheet of the survey with ship and gear characteristics is presented in Table 1. Althought the research ship used was not the oneof the 1983 survey, gear, fishing doars, warps and trawling speed remained the same. In such conditions the effect of using a different ship is reduced to a minimun. Both station election and course are chosen in a non personal proceedings. RESULTS A complete list of species occurrence in comparison with 1989's results is presented in Table 2. Mean catch in half our tow of main species in the bank was: cod Kg American plaice " Sebastes marinus " Sebastes sap " Shrimp " Cod Mean catch by strata and whole bank data and its standard error are presented in Table 3. Cod stock biomass, estimated by sweept area method, was three times bigger than in 1988: This increase of biomass is not explained by individual growth in weight and recritment. The abundances of year classes in the fishery were calculated as follow:

2 - 2 year class abundance ' Ix 10E-4) The higher abundance observed in 1989 was not due to a few tows exceptionaly abundant. The increase observed in the size of the 1987 year class in the 1989 survey may be explained by the increasing retention of longer fish by the gear. Full recruitment to the survey gear seems to occur before age 2. For 1986 to 1983 year classes, the bulk of the population, abundances calculated in 1989 have aproximately the double size than in 1988, if the reduction by natural and fishing mortality is considered. The catches by species (Table 2) remained fairly constant from 1988 to 1989, pointing out that changes in the efficiency of the gear can be considered negligeable. Statistical variability is not also sufficient to explain the higher cod catch. Cod stock biomass estimates compare with USSR's survey results were: Year EEC 1 USSR , , , ,100 12, ,127 7, ,644 36,500 (34,200) (78,300) 1) Biomass estimated from a bottom trawl survey 2) Biomass estimates from bottom trawl survey (Chumakov, A.K PIRO Investigations in AFO Convnnction Area in 198B. AFO SCS Doc. 89/08) 3) USSR's estimates of bottom trawlable plus pelagic biomass (Kuzmin, S.A Stock assessment, age-length composition and maturity stages of the Flemish Cap coda AFO SCR Doc, 90/53) The more feasible explanation for the increase in cod abundance from 1988 to 1989, is that individuals of the strongest year classes in this stock became more accessible to bottom trawl gear in the late year. This would correspond to a less pelagic dispersion. Tables 4, 5 and 6 show length frequency, age length key and estimated age composicion of the stock respectively. American plaice Mean catch by strata and whole bank date. and its standard error are presented in Table 7. Total biomass calculated by sweept are. method was: ,868 t ,533

3 The abundance of year classes in the stock west abundance in: E-3) Full recruitment seems not to occur before age 6. Among the prerecruited year classes, the one of 1986 seems to be very abundant. Tables 8, 9 and 10 - show length frequency, age length key and estimated age composition of the population respectively. Redfish Redfish catches were spitted into Sebaste marinus and Sebastes spn. Scales and otoliths were used for age determination of both species. Mean catch by strata and whole bank data and its standard error are presented in Tables 11 and 15. Sebastes marinus is less abundant than the two other species together. Changes observed in stock biomass may partly arise from incorrect spliting of species in the beggining of 1,88's survey. Stock biomass estimated in: Sebastes marinas 15,289 22,958 Sebastes sdp 142, ,675 total 158, ,633 tons These figures are well below of the respective absolute biomasses due to the pelagic behaviour of the redfish species. Tables 12, 13 and 14 show length frequency, age length key and age composition of the population respectively for S. marinus, and tables 16, 17 and 18 for beaked redfish. Greenland halibut (Reinhardtius hippoolossoides) Mean catch by strata and whole hank estimates are presented in table 19. Table 20 shows the lenght composition of the population. Shrimp (Pandalus borealis) In Table 21. mean catch by strata and whole bank data are presented. Estimated length composition of the population is presented in Tables 22 and 23.

4 Pelagic hauls Last three days of the survey were devoted to make pelagic trawl to identify organisms that are responsables for scathering layers in the echosonder, with special interest in identification of pelagic cod. The hauls were made i.n stations and depths with the most characteristic echo signals. Catches were from eeduses, young Sebastes marinus cod and mictophids. Meduses were present in all hauls. The echo register of pelagic cod, once indentified, corresponded usually to quite large concentrations of fish. REFERECES Doubleday, W.G _ Manual of Groundfish Surveys in the orthwest Atlantic. AFO Sci. Counc. Stud pp. Vazquez, A Results from bottom-trawl survey cf Flemish Cap in July AFO SCR Doc. 89/60, 15 pp. Table 1. Technical data of the survey. Procedure specifification Ship GT Power 8/0 CRYOS 800 t 2 x 690 HP Trawling speed Trawling time Trawl gear footrope / handrope footgear vertical opening warps trawl doors wire length mesh size in codend Type of survey Station selection procedure Criterion to change position of a selected tow: Criterion to reject data from tow Daily period for fishing Species for sampling Species for age determination knot 30 minutes type "Lofoten" / m 27 steel bobbins of 35 cm 3.20 m (according specifications) 100 meters polivalent, 850 Kg 2.5 times the depth 35 mm stratified sampling random - unsuitable bottom for trawling according to ecosoneder register. - information on from previous surveys. - severe tears - less than 20 minutes tow 6.00 to hours all fishes and shrimp cod, American plaice and redfish (Sebastes spp and S. marinus)

5 Table 2. List of species caught in 1988 and Family Species 1988's catch tows number weight(gr) P1SCIS 1989's catch tows number weight(gr), Squalidae Squalidae Squalus acanthias Etmopterus princeps Rajidae Raja sp Raja spinicauda ' Raja radiata Raja senta emichthyidae emichthys scolopaceus Serrivomeridae Serrivomer beani Synaphobranchidae Synaphobranchus kaupi otacanthidae otacanthus chemnitzi (nasus) Chauliodontidae Chauliodus sloani Bathylagidae Bathylagus euryops Argentinidae Argentina silus Stomiidae Stomias boa Paralepididae Paralepis brevis brevis otolepis rissoi Alepisauridae Alepisaurus brevirostris Myctophidae Myctophidae otoscopelus sp Benthosema glaciale Gadidae Gadus morhua Melanogrammus aeglefinus Merluccius bilinearis Urophycis sp Urophycis chus Urophycis tenuis UrophyciA chostcri Micromesistius poutassou 4 4 bit Gaidropsarus ensis Brosme brosme Enchelyopus cimbrius Moridae Antimora rostrata

6 TEAL C Con 'd) Macrouridae Coryphaenoides rupestris Macrourus berglax ezumia bairdi ,Coelorhynchus carminatus Trachyrhynchus murrayi Escomberesocidae Scomberesox saurus Chiasmodontidae Chiasmodon niger Anarhichadidae Anarhichas sp Anarhichas lupus Anarhichas minor Anarhichas denticulatus Zoarc idae Lycodes sp Lycodes esmarki LyCodes reticulatus Stichaeidae Lumpenus lumpretaeformis Escorpaenidae Sebastes sp Sebastes marinus Cottidae Triglops murrayi Cottunculus microps Cottunculus thomsoni Agonidae Aspidophoroides monopterigios Cyclopteridae Cyclopterus lumpus Pleuronectidae Hippoglossoides platessoides Glyptocephalus cynoglossus Reinhardtius hippoglossoides Hippoglossus hippoglossus CEPHALOPODAE Rossia macrosoma Illex illecebrosus Bathypolypus arcticus Histioteuthis reversa Chiroteuthys picteti Cirromorpha Onychoteuthis bauksii CRUSTACEAE Crustaceae se Pandalus borealis

7 Table 3. Cod catches (Kg) by strata. stratum area squa. miles tow number catch per tow mean s.deviat. catch per mile towed mean s.deviat catch per tow catch per mile towed general mean (Y) standard error of Y

8 crl I el O 111 O Ill Mb Cr) C? W Q rl U, rl na O Lin 01 0e en na tt I ri M 1 n en m en DOQOOO 11- r-1 I QQQ CO 11- Ill M) nw tr c4 r1 M r4 14 r-1 O 1 1 r M ry el el C9 CO 01 0 el CD 1/413 r-1 O1P el el el el M M CO rl Co M el '41 re 0 r n C0 CO c-1 O MI CV e4 M cl O 0 01 Table 4. Cod le ngth frequency by strata (x 10E- 4). el O r1 nq CO MI O D 0] M 1/40 el 4-1 el CIEOCOCODO o co en un co I CJ r-1 0 I I l 1 rn 0) 01 I VP 01 0 M 0 O el O r M 4.1 r-4 I 11- rn cr O rci Lin V) LI-) V' 01 1 I M rn on n co * 01 O I I CV CM CO 0 CD 01 M ri 5 I -H a 4-1 I QQ In 0 O 41. 0).41 O 4? co co 1 CO r el CO 0 41' 1/40 ir M 14 1 el M rn 4-1 C) I 0 Ln r, O CO C4 D r-- r-1 0 CM CO in in m O 0* I-1 e11-1 el a) r-- I Q III WC c-i 0 CO 41 D11- r-1 Cr/ el I el.1 el I r-1 r-1 I el el CP CO O 0 M CO el 011 el el 1-I el W I Co 01 CT 0 U ": el 1-- r 0 el I MCI-11-1 I O 0 t-- CO D el 0 M 01 M O 0 0 O 0 0.-I el 1-1 I-1 el O010300C e1 I C D el el 0 CO 0 (0 el I I e1 c-i I.11 LC1 0 1 CO el 1--1 Lel O in m rn I CO, I,-1 Ln ri el M n 0 O O ICI 43 r-i I el el el I ri 0 0 O re) MI rr/ MI 03 CI 0 re) 0 1-I D el 01 PI el 1-I el el M I CO 0. 1/ D O CO el 0 CO 0' 44 1 el v-i el 1-I I-4 1-I I 0 CO M O el I MC 01 CO 01 Cr) 0 MI el I.-I Pl el el el f- 1 I LC1 O M O el CO 0 I CV el 1-4 I 4-IMCOCel el 1 I el CI r- tn Ln o ca 01 0'.4 O t-- M el 44 el 1-1 CV el 4-1 I co -- -a. n o rn te0 ( 0 CO el C) ril OO I LC) CO en el) 0 C CO M el el I I MI I "I. *V tr) III Ln ul VD..0 O r-- r- 03 CO CO CO 01 O CA el 1-I 1-I 011/ II/ O O 0 CO,-1.,), 1-- o on ho mni Lin CO el I. 1". 0 en1dow100.n.er-olnedocilcio3encr 0 0 I c-i -- I en en en I eel en eel en C") I. wr V. In In ire 0 1O 0 10 n 1-- Co CO CO 010 O O I el r el r-i rl

9 Table 5. Cod age length key. age no n id tot length ' ' ' ' total:

10 C (ri al E :rrno0 ed000000ocio rno, 0. 01(3100.0MI fel CO r 1 01 U 1 0) Q l CD CO tfl COOILIel L-1 Lf O CO r-1 el COQ el ti en.0, ece M t in 0 M ld M rl 1Il frl el 9-1 un 0,.. 0 O O CA I 01 0) I LT Ill Lf1 el O T 0 el 0 CO. 01 r en O I I-I MI el CT CO 0 el0 el 1/40 0 Ml 3) A no 4-) a) up 1 0 I LO 1/40 Q f4 1 el CA 0 LC1 M b 1.0 1/40 1l1 10 el 0 LEI el 1.0 CO O C E 0 U 0' un 0 Q CO CT 1.D Zr lt) CT) Q lt1 1/40 el 0. cr. en CO el el 0 ft) 1--1 I O Q 1-1 CO.1,1 VI. 0 el Q Lel CO Lel J I ti 0 Lf) Lil el el 01 o E 4-3 ro!si ni g.'...i en /40 I CO O 0 el CO el el el el el el

11 Table 7. stratum American plaice catch (Kg) by strata. area squa. tow catch per tow miles number mean s.deviat. catch per mile towed mean s.deviat general mean (Y) standard error of Y catch per tow catch per mile towed Table 8. American plaice length frequency by strata (x 10E-3). length stratum (cm) total ,

12 Table 9. American plaice aye length keys. MALE age no n t id tot length total: FEMALE age no n ' id tot length it total:

13 Table 10. American plaice age composition by strata (x 106-3) stratum mean age total weight. 1 : 0 2 : : : : : _ : : : : : ' ' 3 3 t ' 12 : : 14 : 15 : 16+: Table 11. Redfish (Sebastes mantles) catch (Kg) by strata. area catch per squa. tow catch per tow mile towed stratum miles number mean s.deviat. mean s.deviat ' catch per tow catch per mile towed general mean (Y) standard error of Y

14 Table 12. Redfish (Sebastes marinus) length frequency by strata. (x 10E-3) length stratum (cm) total '

15 Table 13. Redfish 1 (Sebastes mar- Inns) age length keys. MALE age length total: no id n. tot

16 16 - TKIOLE (coii ld) FEMALE length age ' total: no id n. tot

17 - (7 - Table 14. Redfish (Sebastes marinas) age composition (x 10E-3). stratum mean age total weight 1 : 0 2 : 0 3 : 0 4 : : : : : : H : : : : : : : Table 15. Redfish (Sebastes spp.) catch (Kg) by strata. area catch per squa. tow catch per tow mile towed stratum miles number mean s.deviat. mean s.deviat ' : general mean (y) standard error of Y cdich per UK./ cdtch per mi I,

18 - is O COCODD OOM0 co cn co r. Ol M s) o M M 101 In LI11-1 V' 00 4D a, r.4 to o Pl 0 I 0 0 CP CO O m r- m co r- co a. O1 o In l tn oo co 01 4 co al PI M l rfl i 40, 01 V rn,-t 01,441 CV P1 40 Cl CO 0 C 1/ cr M 00 0 r- LC) CO C1 M C 1 (0) 4-1 I CO i I CV I 4-41 CV I TT CO 4,14 r- m m ti 1-41 I I O CO ) CO CO CO I I In I '4'1MVUi lo un 0 co cr m o r O al Cr 0 VP 0 C.4 a) r) CV 0 01 I 1-1 IIC1'00C ) I-I Ta ble 1 6. Re d fis h ( Se bas tes spp ) leng th frequency by s tra ta (x 10E- 4). ri 4-1 U1.0 o I r-coouporincotnocno, ,rr oca,c000m), ,-1 Q 414 O)'1'4 C I W 41 4 CO M I I I 1l1,4 O `Tr I 40 CV 00 '04 LE) I-- 0 I PI r-i I I CT 0 c-i 4/23 TO 4,14 01 CO CV 47 0 CO 01'i OD 0) 0O I 00 (-I O 0 0 CV CO in -1 CV I 411 V (01 Cr 01 Ln '4 d 'M,1 4-4 en CV CO CO 01 too1m CV 01 0 CO un 40 m O O C ,1'01 I 1f1 0 th V' 40O CO I-- TT 0101 cn rn 14-1 M 41' CP 0-4 IT1 0 CO 0 I cr I Jl Cl co co 11" (- ct P1 OD 414 I 411 LI1 4, 01 rn r-or-h-c4140co r-omcoct CO M C, o r-- COP1rII 0 Ill CO Ol Tr 41 CT 4-44 CT CO OD 0 CO 0 CI Ot I of O rn co a, o 00 04/ CO a r M m al CV Ol Lrl M I I Ln co o co,r 01 CI4 Ot CM Cl Cn 04) 01 CP 0 CO 0 m r- Ol 0 C). V' CO o M Ln CO 0 (71 In M oo o o 00 CO 00 Cr I C144000C0Cr0 Ol LP IO104D M Ln 10 In.44 Lil c14 M I d'toc CY Cl 0 I-- C`I 0 LC CO CO M 414 PI 41. n o o la CF) l D CO CC I CV CV I M M 01 in w Lf1 M 4,41 a CT O 41 4 O PTI 41. M 10 CI 01 0 I M l0 01 CT) 0 CO Cr,4 C4.4 P1 0 I C I 0 '.-4 4 CV 414 M 4-1 Cr 0 0 LO (V I M CV I E I CV I 01 4 I /1 00 IT el MCr VD IP MMMMMMMM M 4T1 411 Cr '.1'

19 Table 17. Redfish (Sabastes spp) age length keys. MALE age length I total: no id n. tot

20 Twat& /2. (Cant'/) FEMALE no n IS 16± id tot length total:

21 CL 0 0' C) 000O0PC1LC COICD COO.Cr 1/4.0 CO rn 1/4.0 rn IOC CT in S 111 IT CO r- CC O. 0 CL 0 I 0 0 IT TO U CM.. ID M n I I OI r-ltitcot it,h n TO LT,-/ TT1 CO I CO CO r CO L CA CO 0 4D LI) 1-1 PI LT CO 10 I CO,-I TO 01 'CP QI I I IT IT LT CO I 0 LT T-1 I I I I LT T-I LI CO 01 CO CO 01 4 n n C CO in OI CI 0 01 CO Cl CD LII C 4-1 I rn I I 4-1 V C L11 CO 01 I I CO I TO ID 0100 n0 V'rn V Ta ble 18. Re d fis h ( Se bas tes spp ) ag e compos ition (x 1 0E- 4). I-1 1--I 0 T-1 CT CO E C 1.) Le C) Ci 0 I 0 in I LT I 0. CO I 0 LTY 0,t. CO n TT T I1 1-0 O 10 'I' n O 01 co m..cr OIn 0 0 CT TO 4-10'0. I-11-1 I 0 CO O CD 0 CT CO O 10 CO CO CO IT O CT CT, I I CA CO LT 01 CO. 0 4 TO I I I I CO VD 01' 0 CO LT 10 CO 0 Oh In 0 TM 0 OD CO LT LT (71 In rn I I0TICTLI1TO O 01. T Tr UT in (0 LT LT IT I CO CT T in In O 0 OI In in 1000 Ul CO +42 LI) cr F-1 C 0 0 I T CO 1-1, ICOCOOC1COLII TTIL T V in TO I IT TO ' CO. IT VI T Tr L Ln un CP,1 I TO CO (,) in C 1 TO 0) ILO H T '..0 L-4 I M AM In CO CO O n TS in CO I I.-I TY

22 Table 19. Greenland halibut (12einhardtius hippoglossoides) catch (Kg) by sti7ita. stratum area squa. miles tow - number notch mean per tow s.deviat. catch per mile towed mean s.deviat 'catch per tow catch per mile towed general mean (Y) standard error of Table 20. Greenland halibut (Peinhardtius hlppogiossoides) length frequency in the bank (x 10E-3) Sex Sex 1 M H length length '

23 23 - Table 21. Shrimp catch (Kg) by strata. stratum area aqua. miles tow number mctch mean per tow s. deviat. catch per mile towed mean s.deviat general mean (Y) standard error of Y catch per tow catch per mile towed

24 Table 22. Shrimp length frequency by strata (x 10E-4) length stratum (cm) , 19 total

25 Table 23. Shrimp length frequency by sex Ix Sex F length