In a previous paper (Paz and Larrafieta, 1989) we obtained
a significant positive correlation between cod year-class size
in Div. 3NO and American plaice spawning biomass in Div. 3LNO,
that was interpreted by supposing a strong predation of 0-group
cod on 0-group American plaice. On the contrary, we have not
found significant correlations between cod year-classes and
spawning biomasses of other species in the area as redfish,
yellowtail and mackerel.
Following the same method, in this paper we explore
correlations between American plaice (Hippoglossoides platessoides)
and yellowtail flounder (Limanda ferruginea) year-class sizes and
biomasses of adult fishes of these species and those of cod
(Cactus morhua), mackerel (Scomber seombrus) and redfishes (Sebastes
app. 

Larrañeta, M.G. (Manuel Gómez)

Paz, X. (Xabier)

English

Paz, Xabier

Larrañeta, Manuel Gómez

Digital.CSIC

Year-class Variations of American Plaice and Yellowtail Flounder in Div. 3LNO and the Abundance of Other Commercial Fish

Repositorio Institucional Digital del IEO

NOT TO BE CITED WITHOUT PRIOR REFERENCE TO THE AUTHOR(S) Northwest Atlantic Fisheries Organization Serial No. N1850  NAFO SCR Doc. 90/114    SCIENTIFIC COUNCIL MEETING - SEPTEMBER 1990  Year-class Variations of American Plaice and Yellowtail Flounder in Div. 3LNO and the Abundance of Other Commercial Fish  by J. Paz and M. G. Larraneta Instituto de Investigaciones Marinas, Eduardo Cabello 6 36208 Vigo, Spain INTRODUCTION In a previous paper (Paz and Larrafieta, 1989) we obtained a significant positive correlation between cod year-class size in Div. 3NO and American plaice spawning biomass in Div. 3LNO, that was interpreted by supposing a strong predation of 0-group cod on 0-group American plaice. On the contrary, we have not found significant correlations between cod year-classes and spawning biomasses of other species in the area as redfish, yellowtail and mackerel. Following the same method, in this paper we explore correlations between American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea) year-class sizes and biomasses of adult fishes of these species and those of cod (Cactus morhua), mackerel (Scomber seombrus) and redfishes (Sebastes app. ) MATERIAL AND METHODS Data on American plaide recruitment (N 5 ) and spawning biomass (B11+)  in Div. 3LNO (Table 1) have been taken from Brodie (1989), yellowtail flounder recruitment (N 4 ) and spawning biomass (B 6+ ) in Div. 3LNO (Table 2) from Brodie and Walls (1988), cod spawning biomass (B EE ) in Div. 3NO (Table 3) from Baird and Bishop (1989), mackerel biomass referred to Labrador North Carolina area (Table 4) from figure 79.1 in Anon. (1986), and nominal redfish catches in Div. 3LN (Table 5) from Atkinson and Power (1989). These catches were considered as abundance indices of this population. - 2 The possibility of trophic relationships between 0-age groups and juveniles belonging to plaice, yellowtail and other species has been explored by relating the year-class sizes of these species to the adult biomass values of the other species, from one to three years before (negative lag) or after (positive lag) the year of the plaice and yellowtail year-classes. Finally the plaice and yellowtail year-c Lasses are also related to their spawning biomasses, respectively, which gave rise to them, and to their spawning biomasses lagged from one to three years before or after. The year-class is measured at the time of recruitment, N 5 for plaice and N 4 for yellowtail. RESULTS Correlations between plaice recruitment and its spawning biomass are shown in table 6, and between yellowtail recruitment and its spawning biomass in table 7; the only positive and significant correlations are with -2 and -3 year lags for plaice. The correlation coefficients between plaice recruitment and the yellowtail spawning biomass are shown in table 8; positive coefficients appear with 0, 1 and 2 year lags. There is no significant correlation between plaice recruitment and cod spawning biomass (Table 9). On the contrary, positive and highly significant correlations appear between plaice recruitment and mackerel biomass with 0, 1 and 2 year lags (Table 10). Likewise correlation between plaice recruitment and redfish catches was positive and significant with a 1 year lag (Table 11). No significant correlation coefficients appear between yellowtail recruitment and plaice, cod, mackerel and redfish biomasses (Tables 12-15). Finally, table 16 shows the linear regression parameters when correlations have a random probability equal to or less than 0.01. DISCUSSION There were no significant correlations between plaice and yellowtail recruitment and their spawning biomasses (0-year lag in tables 6 and 7). We find no immediate explanation for correlations for plaice with -2 and -3 year lags (Table 6). The positive correlation (Table 8) between plaice recruitment and yellowtail spawning biomass suggests that 0-group plaice prey on yellowtail eggs and larvae, because in the Grand Hank the plaice spawning peak occurs in late April (Pitt, 1966) and yellowtail one in late June (Pitt, 1970); plaice hatching time is 11-14 days at 44C (Bainbridge et al., 1971) and meta- morphosis in Pleronectes platessa , a related species, takes place 120-130 days after spawning time. Yellowtail flounder hatching occurs at the age of 5 days at 10-11VC (Scott and Scott, 1988). It does not seem that the positive and strongly significant correlations between plaice recruitment and mackerel biomass with 0, 1 and 2-year lags (Table 10) can be justified by supposing predation of 0, 1 and 2-group plaice on 0-group mackerel. The 0-group mackerel has a fast growth rate and is a very active predator on eggs and larvae of other fish species; there is even cannibalism between its larvae. On the other hand plaice 1 and 2-groups are benthic, being separated from the pelagic zone which mackerel inhabits. But adult mackerel prey intensively on gadoid eggs and larvae, and because 0-group cod seem to prey significantly on 0-group plaice (Paz and Larrafieta, 1989), the mackerel biomass influence on plaice may be indirect, by reducing the 0-group cod abundance. On the other hand mackerel and plaice spawning areas are separated (Gulf of St. Lawrence and Div. 3N, respectively). But during the winter-spring season, adult mackerel extend to Div. 3N0, since its peak spawning period does not occur until late in June and early July. . Previously (Paz and Larrafieta, 1989) we found a positive and strongly significant correlation between cod recruitment in Div. 3N0 and plaice spawning biomass in. Div. 3LNO, but now, conversely, we do not find any significant correlation between plaice recruit-ment and cod spawning biomass 	the same divisions (Table 9). The positive correlations between plaice recruitment and redfish biomass with 1 and 2-year lags (Table 11) have no easy explanation. Although redfish estrusion larvae occur at 200 m or more on the shelf edge (Bainbridge and Cooper,1971; Akenhead, 1987), it seems very doubtful that redfish larvae are significantly preyed upon by group-1 plaice. In general, there is no significant correlation between yellowtail recruit-ment and the adult biomasses of the other species studied. We have seen that recruitment of some species (species A) is related to adult abundance of other species (species B). The hypothesis is that the 0-groups of species A prey on the 0-groups of species B. However, recruitment of species B is not related to the abundance of adults of. species A. These species pairs are cod(A)-plaice(B) and plaice(A)-yellowtail(B). Let us suppose that a good recruitment is a survival of 100 eggs per female, and that a bad recruitment is 1 egg per female. The relationship between good and bad survival rates will be S /Sb=100, whilst the relationship between mortality rates will be 1-S /1-S b 	That is to say, survival causes (food) could be more important that mortality causes (predation). 4 Summarizing, we find positive and significant correlations between plaice recruitment and yellowtail, mackerel and redfish adult biomasses, but not between yellowtail recruitment and adult biomass of the other species studied (Table 17). This seems coherent with the idea that Div. 3LNO represent the central area of the Hippoglossoides platessoides population in the Northwest Atlantic, and therefore it will be a very integrated species in the Grand Bank ecosystem. In this way plaice popula-tion dynamics could depend very much on the biotic factors in this area. It is in agreement with the important contribution of plaice to the fish assemblages on the Grand Bank (Gomes et al., 1989). However, the presence of yellowtail as a fishery resource in this area is recent, only since the second half of the 1960s (ICNAF Statistical Bull., 1975). Pitt (1970) suggests that the rapid increase in abundance of yellowtail was related to an increase in bottom temperatures and a drastic reduction in the size of haddock stocks, which were apparently competitors of yellowtail. In any case the yellowtail distribution center is south of the Grand Bank, so that its integration into the dynamics of the ecosystem be less mature and its abundance will depend more on physical factors than on biotic ones. ACKNOWLEDGEMENT We are indepted to Dr. T. Wyatt for critically reviewing this manuscript. REFERENCES Anom. 1986. Status of the fishery resources off the North-eastern United States for 1986. NOAA Tech. Mem. MNFS/NEC 43. 130 p. Akenhead, S.A. 1987. Diffusion and redfish larvae on Flemish Cap. Can. Tech. Rep. Fish. Aquat. Sci., 1556:iv+65p. Atkinson, D.B. and D. Power. 1989. Redfish in NAFO Divisions 3LN. NAFO SCR Doc. No. 54, Ser. No. 1634: 26p. Bainbridge V. and G.A. Cooper. 1971. Population of Sebastes larvae in the North Atlantic. Res. Bull. ICNAF, 8: 27-35. Baird, J.W. and C.A. Bishop. 1989. The assessment of the cod stock in NAFO Div. 3N0. NAFO SCR Doc. No. 35, Ser. No. 1611: 61p. 5 Brodie, W.B. 1989. An assessment!lof the American plaice stock in Division 3LNO. NAFO SCR Doc. No. 37, Ser. No. 1477: 51p. Brodie, W.B. and S.J. Walsh. 1988. An update on the status of yellowtail flounder stock in Division 3LNO. NAFO SCR Doc. No. 38, Ser. No. 1478: 42p. Gomes, M.C., R. Haedrich and J.C. Rice. 1989. Fish assemblages on the Grand Bank of Newfoundland. NAFO SCR Doc. 89, Ser. No. 89, Ser. No. 1656: 31p. ICNAF. 1975. Statistical Bulletin for the year 1973. Vol. 23. Dartmouth, Canada: 277p. Paz, J. and M.G. Larraneta. 1989. Cod in Div. 3NO: year-class variations and the abundance of other commercial fish. NAFO SCR No. 72, Ser. No. 1653: 9p. Pitt, T.K. 1966. Sexual maturity and spawning of the American plaice, Hippoglossoides platessoides (Fabricius), from Newfound-land and the Grand Bank areas. J. Fish. Res. Bd. Can., 23: 651-672. Pitt, T.K. 1970. Distribution, abundance and spawning of yellow-tail flounder, Limanda ferruginea, in the Newfoundland area of northwest Atlantic. J. Fish. Res. Bd. Can., 27: 2261-2271. Scott, W.B. and M.G. Scott. 1988. Atlantic fishes of Canada. Can. Bull. Fish. Aquat. Sci., 219: 713p. Table 1 .- American plaice.Div. 3LNO spawning stock biomass (B11+) and recruitment (145). From Brodie (1988). Year. Biomass Recruits class (tons) (000) 1960 236421 1961 211435 1962 189R39 1963 149426 1964 146251 1965 138197 138500 1966 158756 177331 1967 157325 220607 1968 138837 269745 1969 120238 261976 1970 94378 274795 1971 81403 259997 1972 62129 216563 1973 52619 203490 1974 50889 187753 1975 45906 177919 1976 39864 175574 1977 45515 216181 1978 48818 206101 1979 60846 170123 1980 67125 178060 1981 53278 255644 1982 46852 1983 42294 1984 46090 1985 56357 1986 42383 6 Table 2.- Yellowtail flounder Div.3LNO: recruitment (N4) and spawning stock biomass (86+). From table 24 of Brodie and Walls ( 1 988). year 	Biomass 	Recruits class (tons) (000) 1964 	 156799 1965 147013 1966 119893 1967 110606 1968 	25926 	121785 1969 40372 113144 1970 50199 75637 1971 	48747 	71659 1972 33846 79483 1973 24049 83973 1974 	21034 86856 1975 18159 	70496 1976 19152 68298 1977 	18809 121448 1978 21776 	175222 1979 17415 168279 1980 	26325 88426 1981 20530 	55605 1982 16098 12925 1983 	28755 1984 44789 1985 50805 1986 	31474 Table 3.- Cod Div.3N0: spawning biomass (B6+).From Baird and Bishop (1989). Year 	Biomass (tons) 1956 1957 1958 1959 	8840 1960 7234 1961 8974 1962 	8032 1963 8787 1964 11264 1965 	12051 1966 10462 1967 9344 1968 	8268 1969 8026 1970 8137 1971 	8819 1972 7812 1973 7618 1974 	5373 1975 1929 1976 1233 1977 	1655 1978 1948 1979 2628 1980 	5713 1981 8830 1982 9152 1983 	10004 1984 9556 1985 10305 1986 	11069 1987 10990 1988 9120 Table 4.- Mackerel Labrador-North Carolina: population biomass (B1+). From figure 19.1, Anon. (1986). Year 	Biomass (000 tons) 1963 275 1964 311 1965 323 1966 371 1967 623 1968 1198 1969 1533 1970 1856 1971 1868 1972 1653 1973 1389 1974 1126 1975 970 1976 719 1977 491 1978 467 1979 503 1980 467 1981 479 1982 599 1983 695 1984 1078 Table 5.- Redfish Div. 3N: nominal catches (t) from table 1 of Atkinson and Power (1989). Year 	Catch 1959 10478 1960 16547 1961 14826 1962 18009 1963 12906 1964 4206 1965 4042 1966 10047 1967 19504 1968 15265 1969 22142 1970 13359 1971 24310 1972 25838 1973 28588 1974 10867 1975 14033 1976 4541 1977 3065 1978 5725 1979 8483 1980 11663 1981 14873 1982 13677 1983 11090 1984 12065 1985 16880 1986 14971 - 8 Table 6.- Correlation coefficients between plaice recruitment and plaice spawning biomass. Lag -3 -2 -1 0 1 2 3 n = 14 15 16 17 18 19 20 r = 0.763 0.784 0.555 0.132 -0.193 -0.422 -0.514 P = 0.004 <0.001 0.024 0.618 0.450 0.072 0.019 Table 7.- Correlation coefficients between yellowtail recruit-ment and yellowtail spawning biomass. Lag 	-3 	-2 	- 1 	0 	1 	2 	3 n = 	12 	13 	14 	15 	16 	17 	18 r = 	-0.170 -0.268 -0.228 -0.081 -0.022 -0.072 -0.227 P = 	0.606 	0.385 	0.442 0.779 0.936 0.788 0.370 Table 8.- Correlation coefficients between plaice recruitment and yellowtail spawning biomass. Lag 	-3 	-2 	0 	1 	2 	3 n = 	11 	12 	13 	14 	15 	16 	17 r = 	-0.064 	0.165 	0.589 0.701 0.722 0.697 0.390 P = 	0.852 	0.610 	0.026 	0.007 	0.004 	0.004 	0.183 Table 9.- Correlation coefficients between plaice recruitment and cod spawning biomass. Lag 	-3 	-2 	-1 	0 	1 	2 n = 	20 	21 	22 	22 	22 	22 	22 r = 	0.220 	0.091 	0.076 	0.046.-0.008 -0.023 -0,014 P = 	0.328 	0.695 	0.737 	0.839 	0.972 	0.920 	0.950 - 9 Table 10.- Correlation coefficients between and mackerel population biomass. plaice recruitment Lag -3 -2 -1 0 1 2 3 n = 16 17 18 19 20 21 .22 r = -0.364 0.095 0.429 0.692 0.809 0.731 0.475 P = 0.169 0.722 0.075 0.001 <0.001 <0.001 0.025 Table 11.- Correlation coefficients between plaice and redfish biomass 	(catches). recruitment Lag -3 -2 -1 0 1 2 3 n = 20 21 22 22 22 22 22 r = -0.261 0.035 0.271 0.515 0.624 0.542 0.386 P = 0.270 0.880 0.225 0.015 0.003 0.010 0.056 Table 12.- Correlation recruitment coefficients between yellowtail and plaice spawning biomass. Lag -3 -2 -1 0 1 2 3 n = 15 16 17 18 19 19 19 I' 	= -0.105 -0.032 0.126 0.341 0.529 0.565 0.485 p = 0.715 0.907 0.635 0.169 0.019 0.014 0.034 Table 13.- Correlation coefficients between yellowtail recruitment and cod spawning biomass. Lag -3 -2 -1 0 1 2 3 n = 19 19 19 19 19 19 19 r = 0.021 -0.094 -0.124 -0.079 -0.004 0.176 0.297 p = 0.932 0.706 0.619 0.752 0.987 0.477 0.221 - 1 0 - Table 14.- Correlation coefficients recruitment and mackerel between yellowtail population biomass Lag -3 -2 -1 0 1 2 3 n = 17 18 19 19 19 19 18 r = -0.168 -0.346 -0.422 -0.374 -0.275 -0.214 -0.035 P = 0.527 0.162 0.072 0.116 0.259 0.385 0.893 Table 15.- Correlation coefficients between yellowtail recruitment and redfish biomass (catches). Lag 	-3 	-1 	0 	1 	2 	3 n = 	19 	19 	19 	19 	19 	19 	19 r = 	-0.198 -0.330 -0.480 -0.434 -0.207 0.075 0.227 P = 	0.422 	0.170 	0.037 0.063 0.401 	0.763 0.354 Table 16.- Regression parameters, only when P<0.01 Biomass (tons) x Recruits (mill.) y Lag Plaice Plaice -3 160.33 0.6562 Plaice Plaice -2 161.13 0.6618 Yellowtail Plaice 0 151.37 0.2423 Yellowtail Plaice 1 153.79 0.2409 Yellowtail Plaice 2 150.86 0.2411 Mackerel Plaice 0 157.08 54.231 Mackerel Plaice 1 149.38 63.216 Mackerel Plaice 2 155.54 56.997 Redfish Plaice 2 164.51 3.055 Table 17.- Significant correlations (P<0.01) between recruitment and population biomass. In parenthesis year-lag Biomass of 	Recruitment of Plaice 	Yellowtail 	Cod Plaice 	( -2)(-3) ( -1)(0)(1)(2)(3) Yellowtail 	(0)(1)(2) Cod - Mackerel 	(0)(1)(2) Redfish (1) 

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Year-class Variations of American Plaice and Yellowtail Flounder in Div. 3LNO and the Abundance of Other Commercial Fish

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