Fisheries Pêches and Oceans et Océans DFO Science Maritimes Region Stock Status Report D3-17 Species proportion Blueback herring Alewife Bon Harriott Leim & Scott 1966 Gaspereau Southern Gulf Maritimes Region Overview Background Bay of Fundy Alewife (Alosa pseudoharengus) and blueback herring Nova Scotia Coast (Alosa aestivalis) are anadromous clupeids that frequent the rivers of the Maritimes. They are collectively referred to as gaspereau. Blueback herring occur in fewer rivers and are generally less abundant than alewives where both species co-occur. Spawning migrations of alewives typically begin in late April or early May, depending upon The Fishery geographic area and water temperature, peak in late May or early June and are completed by late June or early Landings (t) July. Blueback herring enter the river about 2 weeks later Year 70-79 80-89 1992 1993 1994 1995 1996 than do alewives. Both species return to sea soon after Avg. Avg. spawning. Young-of-the-year gaspereau spend, at most, S.Gulf 3704 4848 4544 4722 3806 3452 2150 the first summer and fall in fresh water before migrating NS.Coast 1279 893 497 803 973 1439 1365 to the sea. Both species recruit to the spawning stock over B. of F. 4184 1836 1618 1137 863 1230 1275 2-4 years. Spawning occurs first in both species at age 3 and virtually all fish have spawned by age 6. The mean TOTAL 9167 7578 6659 6662 5642 6120 4790 age at first spawning is usually older for females than for males. Repeat spawners may form a high proportion (35- 90%) of the stocks of both species, with higher The gaspereau fisheries are regulated by proportions of repeat spawners where exploitation is low. season, gear, and license restrictions. Few Gaspereau are harvested by gill, trap, and dip nets new licenses have been issued since 1993. depending upon the river and location within the river system, e.g., gill net in the river mouth, dip net in the Individual licenses may be for multiple and lower river, and trap net in lake areas. Special tip-traps variable units of gear. The primary measures are used in the Margaree River and square-nets are used restricting exploitation rates are a limiting of in the Gaspereau River. licenses to existing levels in all areas and a In the absence of specific biological and fisheries information, the management target is to maintain two-day per week closure. Variations from harvests at about long-term mean levels. Some stocks are the general closures and restrictions are assessed in greater detail and the management target is instituted under river-specific management defined on the basis of a fishing mortality level which does not exceed the natural mortality rate (equivalent to plans. The potential for bycatch of Atlantic exploitation rates of 0.33 to 0.39). The Saint John River salmon and striped bass is of concern, stock at Mactaquac is managed on the basis of a fixed particularly in the Miramichi and Saint John escapement target derived from analysis of stock and rivers, where various restrictions, e.g. fishing recruitment data. season adjustments, and minimum fish length September 1997 Maritimes Region Gaspereau Maritimes Region Overview limits, are implemented. Logbooks are There are large variations in annual landings issued to fishers in the Bay of Fundy and but few statistically significant trends. Nova Scotia Coast areas as a condition of Exceptions to this are the Saint John River, license, but are not issued in the Southern Margaree River, Gaspereau River, Mersey- Gulf area of New Brunswick. Medway area and the eastern shore of Nova Scotia where landings have declined. Gaspereau fisheries in the Maritimes are Landings in the Tusket River have increased geographically and economically diverse. recently. Reliable harvest information is available only for a few of the larger fisheries. In many Trend 1970-1996 areas, gaspereau used locally as bait for Avg. Harvest 1987 to 1996 Up Down Same other fisheries may not be registered in the > 1000 t purchase slip database. Logbook programs 100 to 1000 t may record a large portion of the catch; the < 100 t participation rate is generally between 75% and 90%. Reported landings from the Maritimes peaked in 1980 at just under 11,600 t. A second peak in 1988 of just under 10,500 t has been followed by a continuous decline to less than 5,000 t in 1996. In the last ten years, the Southern Gulf harvests have represented between 45% and 71% of the total Maritime harvest. 12,000 10,000 Bay of Fundy Resource Status 8,000 Southern Gulf 6,000 Harvest (t) 4,000 Nova Scotia Two major fisheries of the southern Gulf Coast have been monitored annually since 1983: 2,000 Southern Gulf the Miramichi River in New Brunswick and 0 the Margaree River in Cape Breton, Nova Scotia. Less intensive and generally 1960 1963 1966 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 opportunistic sampling has been conducted on three other fisheries in New Brunswick: The most important fisheries occur in the Richibucto, Tracadie and Pokemouche Saint John River (Bay of Fundy, NB) and the rivers. Miramichi River (Southern Gulf NB). In most parts of the Maritimes, gaspereau In the Miramichi River fishery, gaspereau fisheries are relatively small (less than 100 t catch composition varies annually between annually). 24% and 77% alewife by number. The current 36 licensed trapnets in this fishery 2 Maritimes Region Gaspereau Maritimes Region Overview has remained relatively constant in number classes, either as 4-year olds or 5-year olds, since 1970. The reported harvest of making up between 34% and 77% of the gaspereau has increased slightly since the total annual catch. Blueback herring have a early 1980s and has averaged about 2000 t in wider distribution than do alewife, with ages the last five years. ranging between three and ten years old. The 1992 year-class of blueback herring is weak, 4000 as evidenced by the low catches of three-year Miramichi olds and four-year olds in the fisheries of 3000 1995 and 1996. 2000 80% Blueback herring 1996 Harvest (t) 1000 60% 1993 1995 1994 0 40% 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 Percentage 20% First-time-spawners (FSP) have comprised 0% between 37% and 87% of the alewife catches 3579 3579 3579 3579 (median 72% between 1982 and 1996). Alewife are predominantly harvested as 4- Age (years) year olds and these make up 35% to 79% of The fewer age-classes in the alewife the annual harvest. Fewer than four cohorts spawning run compared to blueback herring generally contribute to the alewife harvest, is indicative of a higher mortality rate for with few alewife older than six years in the alewife. Exploitation rates for alewife and fishery in recent years. Few three or four blueback herring were estimated after year olds of the 1992 year-class have been assuming a natural mortality rate of 0.4. The caught, and the year-class is considered to be assumption of equal natural mortality rates very weak. for both species implies that differences between species in total mortality are due to 80% different exploitation rates. Annual Alewife exploitation rates on alewife have varied 60% between 0.39 and 0.76, above the target 1993 1994 1995 1996 exploitation rates of 0.33 to 0.39. Blueback 40% herring exploitation rates have generally been Percentage lower than on alewife, varing between 0.12 20% and 0.62 and frequently less than the target exploitation rates. 0% 3579 3579 3579 3579 Age (years) FSP in the blueback herring catches have generally been lower than for alewife, varying between 17% and 71% (median 48% during 1982 to 1996). Blueback herring catches are also dominated by single year- 3 Maritimes Region Gaspereau Maritimes Region Overview 0.8 catch for the year at the index trapnet occurred after June 20. 0.7 0.6 In the Margaree River, alewife make up 0.5 more than 95% of the garpereau harvest. 0.4 Alewife have returned to the river as early as 0.3 mid-April but the major run occurs in the Exploitation Rate (ER) 0.2 Blueback herring second to fourth weeks of May. Historically, Alewife 0.1 Target ER (Minimum) the harvest peaked in 1988, and has declined Target ER (Maximum) 0 precipitously since, largely due to the 1982 1984 1986 1988 1990 1992 1994 decreased abundance of gaspereau. The reported harvest of 94 t in 1996 is the lowest The lower exploitation rate on blueback since 1957. herring is a consequence of the later spawning migration of blueback herring 2,000 relative to alewife (about two weeks) and the Margaree closure of the fishery in mid-June when only 1,500 a portion of the blueback herring stock is available to the fishery. 1,000 Harvest (t) Since 1990, the fisheries as described by the 500 date when 50% of the annual catch was taken, have occured later than in the 1980s. 0 1977 1982 1987 1992 1997 Loggieville Chatham Newcastle Since 1990, the fishery has occurred mostly 15-Jun in the latter part of May and beginning of June in contrast to the 1980s when a large 05-Jun portion of the fishery occurred in May. The fishery in 1995 was the latest on record with Median date 26-May a median date of harvest of June 6. 13-Jun 16-May 84 87 90 93 96 84 87 90 93 96 84 87 90 93 96 03-Jun Year and Location In 1995 and 1996, a later timing of the 24-May fishery was expected because of the delay of Median date the season from May 15-June 15 to May 20- June 20.