3rd Bay of Fundy Science Workshop
Understanding Change in the Bay of Fundy Ecosystem
Environmental Quality and Aquaculture
Nutrification in the Bay of Fundy: Sustainable Integrated
Aquaculture as one of the Bioremediation Tools
Salmonid Aquaculture Mortalities and a Bloom of Mesodinium
rubrum in Passamaquoddy Bay in 1998
Effects of Different Effluent Streams from a Bleached Kraft Pulp
Mill on Fundulus heteroclitus
A Review and Update of Aquaculture Impact Studies Carried Out on
the Magaguadavic River, Southern Bay of Fundy, New Brunswick
Nutrification
in the Bay of Fundy: Sustainable Integrated Aquaculture as one of the Bioremediation Tools
Thierry Chopin¹ and Charles Yarish²,
¹University of New Brunswick, Centre for Coastal Studies and
Aquaculture,
Department of Biology, P.O. Box 5050 Saint John NB E2L 4L5
²University of Connecticut, Department of Ecology and Evolutionary Biology,
One University Place, Stamford CT 06901-2315 USA
Abstract
Nutrification of coastal waters as a result of anthropogenic activities is a worldwide phenomenon. In the Bay of Fundy, the salmon aquaculture industry is one of the contributors to significant nutrient loading. This monospecific type of aquaculture is presently at a crossroad, as its economic and environmental limitations are realized and its sustainability questioned. The development of integrated aquaculture practices appears more and more necessary and timely, in light of the several crises experienced by finfish aquaculture in recent years and rising concerns by the public over its impacts. The bioremediation role of seaweeds, acting as biological nutrient removal systems and the mutual benefits for co-cultured organisms are becoming better understood. Our results show that the productivity, and the phosphorus and nitrogen uptake of the red alga Porphyra are sufficiently high to make it an excellent choice for integrated aquaculture for bioremediation and economic diversification. Its regular harvesting amounts, on one hand, to constant removal of significant quantities of nutrients from coastal waters, and, on the other hand, to the production of marine crops of high added value. The development of integrated aquaculture will, however, only come about if there is a major change in social, economic, political, and funding reasoning by seeking sustainability, long-term profitability, and responsible management of the coastal zone through research for the development of innovative bio-engineering concepts and practices.
Salmonid
Aquaculture Mortalities and a Bloom of (Mesodinium rubrum) in Passamaquoddy Bay in 1998
Jennifer L. Martin, F. H. Page, S. Robinson, M.M. LeGresley and M. Ringuette ,
Fisheries and Oceans Canada, Biological Station, St. Andrews NB E0G
2X0
Abstract
A red tide caused by the organism Mesodinium rubrum was observed in Passamaquoddy Bay in 1998 during the three weeks of late August through mid-September, 1998. Brick-red blooms of the planktonic ciliate have been observed in the past in many coastal regions throughout the world, including Passamaquoddy Bay. M. rubrum concentrations observed from water samples collected during the bloom period exceeded 1 million cells*L-1 in areas of water discolouration with dense concentrations observed to a depth of 10 m. The dominant organism in samples was M. rubrum and it represented up to 95% of the total algal population.
Although M. rubrum does not produce a toxin, it is possible for mortalities to occur through secondary effects, such as asphyxiation, as a result of oxygen depletion. During the bloom period, the red tide drifted through a number of salmonid aquaculture sites resulting in low level mortalities.
Discrete water samples collected for phytoplankton identification and enumeration revealed concentrations of M. rubrum greater than 1 million cells*L-1 at various locations in Passamaquoddy Bay. Sigma-t profiles indicate that the water column was stratified during August and well mixed during September.
Effects of
Different Effluent Streams from a Bleached Kraft Pulp Mill
on (Fundulus heteroclitus) Monique G. Dubé and Deborah L.
MacLatchy ,
University of New Brunswick, Department of Biology
P.O. Box 5050, Saint John, NB E2L 4L5
Abstract
Reproductive dysfunction has been documented in wild fish populations exposed to bleached kraft pulp mill effluents in Canada and Scandinavia. Effects documented included decreased gonad size and fecundity, increased age to maturation, decreased reproductive steroid hormone levels, and altered expression of secondary sexual characteristics. The source of contaminants causing the dysfunction is unknown. The final effluent, which is discharged from a pulp mill, contains a complex mixture of contaminants arising from different stages in the pulping process (i.e., condensate recycling, brownstock washing, bleach plant). In 1997, mesocosm studies commenced at a pulp mill in Saint John, New Brunswick to determine the effects of different effluents from the pulping process on the reproductive status of a fish species endemic to the St. John River estuary. Final effluent discharged from the mill decreased circulating reproductive steroid hormone levels in the mummichog. In 1998, the mill installed a reverse osmosis system to treat approximately 1100 USgal/min of clean condensate from the fifth effect evaporator that is recycled for brownstock washing. The reverse osmosis system had significant effects on final effluent quality resulting in approximately 2000 kg/d and 4000 kg/d reductions in biochemical and chemical oxygen demand, respectively. More importantly, the final effluent is non-acutely lethal to rainbow trout and the invertebrate Daphnia magna. In addition, sublethal toxicity levels (IC25s) of the final effluent, to three marine test species, are among the lowest when compared to mills that employ secondary effluent treatment. Plasma steroid hormone depressions are also no longer apparent in fish exposed to environmentally relevant (1%) concentrations of the final effluent. Installation of the reverse osmosis system has been an environmentally significant process change because, in the absence of secondary effluent treatment, it has significantly contributed to achieving compliance with environmental effluent regulations for acute lethality and has reduced sublethal reproductive effects in a native fish species. Further studies are underway in an attempt to reproduce the results of these studies.
A Review and
Update of Aquaculture Impact Studies Carried Out on the Magaguadavic River, Southern Bay
of Fundy, New Brunswick Fred Whoriskey¹, Jonathan Carr¹, Gilles
Lacroix² and Michael Stokesbury³,
¹Atlantic Salmon Federation, P.O. Box 429, St. Andrews NB E0G 2X0
²Dept. Of Fisheries and Oceans, Biological Station, St. Andrews NB E0G 2X0
³Acadia University, Department of Biology, Wolfville NS B0P1X0
Abstract
The Magaguadavic River is located near the heart of the North American East Coast aquaculture industry, and monitoring work here provides the best data set for this region on the potential frequency of interaction between aquaculture and wild Atlantic salmon. Aquaculture fish may enter this river by escaping from hatcheries located within the watershed or after their escape from sea cage sites.
Wild salmon returns have steadily declined from 293 in 1992 to 31 fish in 1998. By contrast, escapees have composed from 34% to 90% of the annual salmon returns in this period. Only an estimated 13.5% (average 1992-1998) of the cultured salmon entering the river were classified as sexually mature, based on secondary sexual characteristics and/or hormonal assays. By contrast, all wild salmon were maturing and exhibited secondary sexual characteristics by mid August.
Juvenile salmon densities and relative abundance have been low at most sites examined. Higher numbers of parr caught near salmon hatcheries may have been due to juvenile escapees. Hatchery escapees dominated 1998 smolt samples.
Escaped adults caught in the fishway were transplanted to sites up to 48km away to see if they would home back to the river. In 1997, 1 of 78 fish returned. By contrast, in 1998, 31 of 146 fish (21%) made their way back. Homing to rivers by escapees has not been previously reported.
No pathogenic bacterial or viral organisms were found in wild and cultured salmon tested during 1992-1996. However, in 1997, 5 of 34 cultured salmon tested were suspect for hemorrhagic kidney syndrome (HKS). In 1998, 1 of 61 fish screened for viral and bacterial diseases tested positive for BKD. No positive tests for pathogenic virus have been reported.
Juvenile salmon densities and relative abundance have been low at most sites examined. Higher numbers of parr caught near salmon hatcheries may have been due to juvenile escapees. Escaped juveniles from hatcheries within the watershed dominated 1998 smolt samples.
Introduction
This review summarizes our most recent data on the interactions between wild and cultured Atlantic salmon (Salmo salar), in the Magaguadavic River, New Brunswick. The huge growth of the salmon aquaculture industry, and of escapees from the sea cages, could negatively affect wild salmon through genetic (foreign gene introductions) or ecological (competition, predation) swamping, and/or disease introductions. Our work aims to help provide a factual basis for planning and decision making.
The Magaguadavic River is situated near the center of the North American East Coast Atlantic salmon aquaculture industry, and large numbers of escaped cultured salmon from sea-cages have entered the river in recent years. Three commercial salmon hatcheries that together produce about two million smolts for the sea-cages are located within the drainage, and cultured juvenile salmon are escaping from those sites.
Methods
The study site
The Magaguadavic River is the sixth largest river in New Brunswick. It originates in the Magaguadavic Lake in the southwest part of the province and flows southeasterly 97 km to Passamaquoddy Bay (an offshoot of the Bay of Fundy) near St. George. There are 103 named tributaries and more than 55 lakes within a drainage area of 1812 km². A 13.4 m high dam (built in 1903) located at the head of the tide is equipped with Francis runner-type turbines which generate about 3.7 megawatts of power. A pool and weir fishway bypasses the dam for upstream fish passage. A sluiceway intended for downstream fish passage is situated adjacent to the penstock. Water storage reservoirs are located in Mill, Digdeguash, and Magaguadavic Lakes.
Sampling regimes
Details on the salmon of the Magaguadavic River and methods used for our work are found in Carr (1995), Carr et al. (1997) and Carr and Whoriskey (1998). Briefly, all salmon arriving at the Magaguadavic River from the ocean must past through a fish ladder which bypasses a head-of-tide dam built in 1903. Complete counts of the river's salmon run have been made in the fish ladder's trap since 1992, and some historical counts are also available. Wild salmon ascend the river from June until early November. Spawning occurs from late October until mid November. Wild salmon spend 2 to 4 years in the river before they migrate to sea as smolt (Carr 1995). Fish captured in the fishway can be tagged, sexed, screened for sea lice or sampled for disease testing, and/or prepared for transplanting. Juvenile salmon were caught by electrofishing or in a fyke net during the smolt run.
Results
Wild and escapee returns
Counts of wild salmon have declined from 293 in 1992 to 31 in 1998 (Figure 2). Total wild returns in 1998 were only 27% of the average return of 115 fish in the 1993 to 1997 period. In the 1980s, wild returns were over 800 fish. The six year average (1992-1997) of repeat spawners in the wild salmon run was 7%. No wild repeat spawners returned in 1998.
Wild salmon entered the river from June through November and numbers generally peaked in July or August (from 1992-1998). By contrast, cultured escapees entered the river later than wild fish in all years and their numbers peaked in either September or October.
The number of escapees entering the river have ranged from 119 (1997) to a peak of 1200 in 1994. A Passamaquoddy Bay sea-cage failure in 1994 resulted in the escape of an estimated 20,000 fish. This probably accounts for the increased numbers of cultured salmon entering the Magaguadavic River in 1994 and 1995.
Spawning of escapees
In 1993, eggs were sampled from 20 redds, and analyzed for carotenoid pigments. Of these, 45% of the redds were made by wild females, 20% by escaped aquaculture females, and the remainder had pigments suggesting a possible aquaculture origin.
Two escaped MSW cultured salmon repeat spawners have been captured in the fishway: one male in 1992, and one female in 1994. It is not known if they had spawned in the Magaguadavic River, or elsewhere.
Since 1997, no aquaculture origin fish have been knowingly passed upstream through the fishway.
Transplants of escapees
In 1997 and 1998, 78 and 144 cultured salmon respectively were Floy-tagged and released at various sites in Passamaquoddy Bay to determine whether they had entered the river at random or would home back to it if re-released.
In 1997, only one of the 78 fish (1.3%) was recaptured in the Magaguadavic fishway. This was a 73.8 cm male released in the river's estuary, at the site closest to the fish ladder. An unintended control was obtained when two male wild grilse were accidently classified as escapees and transplanted. Both returned to the fishway trap two and six days after release, from distances of 9.3 km (6 days later, 1.55 km/day) and 22 km (3 days later, 7.3 km/day).
By contrast, in 1998, strong fractions of both the small (<=63 cm) and larger (>63 cm) salmon returned to the river following their initial transplantation. A significantly (X², P <0.05) larger fraction of large (27%) than small (13%) salmon came back.
Pooling small and large salmon data, similar (X², P > 0.25) fractions of males (16.7%) and females (24%) returned after their first transplant.
Large and small salmon which had returned following a first transplantation were moved a second, and in some cases a third time. On each occasion, they were placed at a different site. For both the large and small fish that repeatedly returned to the Magaguadavic River fishway, rates of travel remained similar. However, while the number of fish returning fell after each transplant for both large and small salmon, in the small salmon category, the fraction of the fish returning increased with each transplant event. In addition, the returning fish tended to be the largest of the small fish. By contrast, for the large salmon, the fraction of fish returning did not increase with successive transplantation events and the sizes of returning fish did not trend upwards.
State of Maturity
On average, 11.1% of cultured salmon from the 1992-1998 period were classified as sexually mature (range 3.3% in 1994 to 46.2% in 1997) (see also Lacroix et al. 1997).
An increased frequency of escaped cultured postsmolts was observed in the river beginning in 1994, after the establishment of a brackish water rearing site near the mouth of the Magaguadavic River. Sexually precocious males comprised over 50% of the postsmolts in 1995 and 1997.
Disease Screening
Viruses and Bacteria
Deliberate killing of aquaculture escapees for disease screening was done in 1995, 1997 and 1998. Post mortem examinations/disease culturing were conducted either by the New Brunswick Department of Fisheries and Aquaculture (St. George), or the Department of Fisheries and Oceans (Moncton).
Tissue samples of kidney, spleen, gills, and pyloric caeca were extracted from 61 escapees in 1995, and sent to the Department of Fisheries and Oceans for virus screening. All tests were negative.
In 1997, 5 of 34 cultured salmon examined were suspect for HKS (Hemorrhagic Kidney Syndrome, now termed Infectious Salmon Anemia or ISA) based on visual inspection of pathologies in post mortem exams. Unfortunately, no viral cultures were done on these fish. No other pathologies were noted in post mortem exams or in cultures conducted on the other fish, including 19 sent to DFO for viral screening.
In 1998, 60 escapees were sent to the Department of Fisheries and Oceans for viral and bacterial screening. To date, one fish tested positive for a bacterial pathogen (BKD). No positive virus tests were recorded.
Occasional disease screening of incidental mortalities at the fishway was also done in the 1993 - 1996 period. Of seven wild mortalities, six showed no pathogens and one tested positive for vibrio. All escapees tested in the same period were clean (N=124).
Sea lice
No trends with time were evident in our sea lice counts. The majority of fish, both wild and escapees, had no or low levels of infestation with sea lice in all years. However, we do not know for how long the fish were resident in the river before they moved into the fish ladder trap. The lice may have dropped off before they could be counted.
Juvenile Salmon Escapes
In 1998, 1185 smolts were captured, of which 82% were classified as hatchery escapees. An additional 15% were of Magaguadavic origin (including clipped fish from a satellite rearing program that used Magaguadavic River broodstock), and 2.6% were landlocked salmon that had been fin clipped and stocked in lakes in the system, and nevertheless were moving out to sea. Stokesbury and Lacroix (1997) also reported high numbers of escaped hatchery smolts from this river in 1996.
Electrofishing for parr have found them to generally be rare, with the largest catches being composed of hatchery escapees in the vicinity of the hatcheries (Carr and Whoriskey 1998).
Conclusions
1. The Atlantic salmon population of the Magaguadavic River, similar to that of other rivers draining into the Bay of Fundy, is in an extremely fragile state. Returning adults are providing a small fraction of the required egg depositions and wild juvenile numbers are low. This makes these rivers particularly vulnerable to the impacts of influxes of non-native fish.
2. Aquaculture escapees now far outnumber wild fish in Magaguadavic fish ladder counts, although their annual numbers vary greatly and unpredictably. In the past, these fish have spawned in the river and have probably mixed their genes with wild fish. Meanwhile, wild juveniles are also being swamped by fish escaping from hatcheries in the system. In European work, genetic and ecological swamping have been implicated in negative fitness effects on wild salmon populations (Fleming and Einum 1997, McGinnity et al. 1997). We have not had the resources to conduct similar work in the Bay of Fundy region.
3. In 1998, systematic disease screening suggested a low frequency of disease for the escapees. However, viral cultures are still being conducted. In 1997, five escapees had symptoms consistent with ISA, but no viral cultures were done on the fish and the conclusion is uncertain. In all years, the great majority of escapees examined did not test positive for diseases. This suggests that aquaculture fish may pose a limited risk of carrying diseases to freshwater. Sea lice counts were also low on returning fish. However, none of our work can address the possibility that wild fish at sea might pick up and die from diseases which originate at cage sites. We are only screening the survivors.
4. In one of two years, transplanted aquaculture fish showed a degree of homing and returned to the Magaguadavic River. This had not been reported from other salmon farming areas. These fish may have been raised to the smolt stage in one of the hatcheries located in the system and hence have imprinted to it. The fact that many of them were not maturing shows that homing ability is decoupled from the reproductive cycle.
Given the fragile state of the wild fish of this river and of other rivers in the Fundy region, we must minimize interactions among wild and aquaculure fish.
References
Anon. 1978. Biological Conservation Subcommittee Report. Prep. For Atlantic Salmon Review Task Force. 203pp.
Carr, J. 1995. Interactions Between Wild and Aquaculture Atlantic Salmon in the Magaguadavic River, New Brunswick. M.Sc. Thesis, University of New Brunswick, Fredericton: 77 pp.
Carr, J. and F.G. Whoriskey. 1998. Atlantic Salmon (Salmo salar) in the Magaguadavic River, New Brunswick. Atlantic Salmon Federation Research Report.
Carr, J.W., J.M. Anderson, F.G. Whoriskey and T. Dilworth. 1997. The Occurrence and Spawning of Cultured Atlantic Salmon (Salmo salar) in a Canadian River. ICES J. Mar. Sci. 54:1064-1073.
Fleming, I.A. and S. Einum. 1997. Experimental Tests of Genetic Divergence of Farmed From Wild Atlantic Salmon due to Domestication. ICES J. Mar. Sci. 54:1051-1063.
Lacroix, G.L., B.J. Galloway, D. Knox and D. MacLatchy. 1997. Absence of Seasonal Changes in Reproductive Function of Cultured Atlantic Salmon Migrating into a Canadian River. ICES J. Mar. Sci. 54:1086-1091.
McGinnity, P., C. Stone, J.B. Taggart, D. Cooke, D. Cotter, R. Hynes, C. McCamley, T. Cross and A. Ferguson. 1997. Genetic Impacts of Escaped Farmed Atlantic Salmon (Salmo salar) on Native Populations: Use of DNA Profiling to Assess Freshwater Performance of Wild, Farmed and Hybrid Progeny in Natural River Environment. ICES J. Mar. Sci. 54:998-1008.
Stokesbury, M.J. and G. Lacroix. 1997. High Incidence of Hatchery Origin Atlantic Salmon in the Output of a Canadian River. ICES J. Mar. Sci. 54:1074-1081.
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