Download Summary of Conference in AIC-Conference-2007 (PDF)

Primary Author:
Jason Hallett
University of New Brunswick
Fredericton, NB
[email protected]

Contributors:
David Cairns

Title: Is the American eel primarily a marine species?

Recent otolith microchemistry studies have shown that some American eels (Anguilla rostrata) complete their life cycles in marine waters. However, Anguilla eels are still referred to as “freshwater eels,” implying that the majority occupy fresh water during the growth phase of their life cycle. We estimated eel populations in selected areas of the southern Gulf of St. Lawrence using electrofishing, mark-recapture, and nighttime surveys with a glass-bottom boat. Electrofishing surveys indicate a total of 972,000 eels in riverine habitat in southern Gulf drainages. Prince Edward Island has 39,000 ha of sheltered bay and estuary habitat with a depth less than 3 m. Based on densities derived from mark-recapture and glass-bottom boat surveys, the population of eels in marine habitats in PEI exceeds the population of eels in freshwater in all southern Gulf drainages. There are 65,000 ha of shallow and sheltered bay and estuary habitat in eastern New Brunswick. Patterns of commercial fishing effort suggest that most of this habitat is occupied by eels. There are also very large amounts of sheltered estuary and bay habitat elsewhere in eastern North America, especially in the eastern U.S. The American eel may be primarily a marine species, with only an atypical minority using freshwater as growth areas.

Primary Author:
John L. MacMillan
Nova Scotia Department of Fisheries and Aquaculture
Pictou, NS
[email protected], [email protected]

Contributors:
Reginald J. Madden

Title: Biological Characteristics and Population Status of Anadromous Brook Trout (Salvelinus fontinalis), 66 Years after an Initial Study in Moser River, Nova Scotia, Canada

Brook trout Salvelinus fontinalis are the most popular native sport fish in Nova Scotia. A decline in the annual catch of brook trout since the early 1980s may reflect a change in the resource. Nova Scotia’s relatively short river systems are believed to facilitate anadromy in many brook trout populations and these trout are important to the sport fishery. Live release traps and water quality measurements were used to assess brook trout population parameters and habitat in the same locations as in the historical studies conducted on the Moser River by Leverin (1939), White (1940 and 1941), Huntsman (1942), and Wilder (1952). In 2006, the timing of anadromous brook trout migration was similar in comparison to White’s study: downstream migration occurred in May and most upstream migration occurred in July. However, a greater proportion of upstream migrating brook trout were detected in June in 2006 compared to June of 1939 to 1941. The number of brook trout trapped per day in Mill Brook, a major tributary of Moser River, suggests that the median number of anadromous brook trout had declined in 2006 (1.5) compared to 1940 (9.5) and 1941 (18). A significant difference was detected in the number of brook trout trapped per day in 2006 compared to 1940 and 1941 (P< 0.05). Relative stock density of brook trout indicated that large trout in the 2006 population was less than that of historical levels. The proportion of brook trout (fork length >300 mm) captured migrating upstream was 3% in 2006 which was significantly less than 26% in 1940 (P< 0.05), and 27% in 1941 (P< 0.05). In 2006, fork length of anadromous brook trout was 221 mm ±25 (mean, SD) at two years of age and 276 mm ±34 (mean, SD) at three years of age and was similar to mean fork length at age from 1939 to 1943. The oldest brook trout aged was four years in 2006 and six years in 1939 to 1943. A maximum age of four years, for the 2006 study, was consistent with other recent studies on anadromous brook trout populations in Nova Scotia. During low flow periods in August, Moser River pH was 6.5 (0.35,SD) in 1939 and was 5.7 (0.15, SD) in 2006. Diatom inferred pH from a paleolimnological assessment of Mill Lake, located upstream of the Mill Brook trapping site, indicated an increase in acidity by a decline of pH 0.7 units from pH 6.8 in the 1930s. Diatom inferred Gran alkalinity changed from a pre impact range of 4.1 7.2 mg/L to a present day 0.6 mg/L (Ginn, Personal communication). Water temperature was warmer in 1939 compared to that in 1940 41 and 2006. In 1937 and 1939, mortality of salmon and trout in the Moser River occurred during warm low flow conditions (Huntsman 1942). A warming trend occurred over the past 140 years and the summers of 1937 and 1939 were two of the warmest on record for the Halifax region (Environment Canada). Changes in environmental conditions and exploitation may have influenced the size and age structure of the Moser River anadromous brook trout population.

The authors wish to thank the many professionals, volunteers and concerned anglers who participated in this project. Gordie Greencorn and Al McNeill, Nova Scotia Department of Fisheries and Aquaculture, Gerald Hardy, Gordie Naugler, Jim Lowe (Fisheries and Oceans Canada ), Arth Jewers, and Darren Pace all contributed to the data collection component of this study. Special thanks to Brittany Curry for her extensive fieldwork and Eddie Halfyard and J.P. Hastey for their assistance during the project. Peter Amiro, Fisheries and Oceans Canada, Science Branch, for providing White’s (1939-41) raw data allowing for a comprehensive comparison. We acknowledge Murray Hill and Don MacLean Nova Scotia Department of Fisheries and Aquaculture for providing resources for this survey.

Primary Author:
Jason LeBlanc
Nova Scotia Department of Fisheries & Aquaculture
Pictou, NS
[email protected]

Title: Historical changes in the distribution of smallmouth bass, Micropterus dolomieui, in Nova Scotia and preliminary assessment of nesting success

Smallmouth bass in NS have expanded their distribution by a factor of 20 since the first introductions into 9 lakes from 1942-1953. Additional areas were stocked in 1967 and two other lakes in 1971 and 1984. Despite not all stockings being successful and no further authorized introductions, there are now approximately 200 lakes containing bass in NS as a result of dispersals within watersheds, illegal introductions and accidental transfers. Geographical differences within NS causing temperature gradients, and limited growth potential may restrict or exclude colonization in several areas. A total of 493 nests were monitored in 8 lakes over a three year period. The percentage of successful nests ranged from 9.8 to 70.0. Habitat modeling identifies wildlife suitability corridors for dispersal within watersheds. A project to predict the likelihood of colonization of lakes not currently inhabited by bass was attempted using lake characteristics such as shoreline development and area.

Primary Author:
Eva Walker
Parish Geomorphic / UNB
Fredericton, NB
[email protected]

Title: Circulating glucose dynamics and stress response to acute stress in two Percids: Johnny darter (Etheostoma nigrum) and yellow perch (Perca flavescens).

Relatively little research has examined the glucose dynamics and stress responses, more specifically blood glucose, in small-bodied fish. Research examining glucose dynamics has taken place in the laboratory or hatchery and concentrates on large economically important species. Stream-side mesocosms were used to examine glucose regulation and the physiological stress response to suspended sediments in Johnny darter (Etheostoma nigrum) and juvenile yellow perch (Perca flavescens) over a 24 h period. Fish were subjected to a chase stressor and different concentrations of suspended sediments (0, 35, 350, 1500 and 3500 mg/L) as an environmental stressors. Stress was measured as changes in circulating blood glucose levels. Confinement without food increased glucose levels in both species, Johnny Darter (JD) from 3.5 ± 0.7 mmol/L at capture to 6.56 ± 0.9 resting and yellow perch (YP) 4.9 ± 0.3 mmol/L at capture to 6.4 ± 0.4 resting. Feeding did not appear to strongly influence glucose levels in JD. Yellow perch glucose levels showed sight regulation. Mean glucose level in Johnny darter at of 35 mg/L was slightly but significantly lower (5.1 ± 0.2 mmol/L) than zero turbidity controls (5.4 ± 0.2 mmol/L) and fish exposed to 350 mg/L (6.1± 0.3 mmol/L), 1500 mg/L (6.2 ± 0.3 mmol/L) and 3500 mg/L (5.4 ± 0. 2 mmol/L). The lower glucose levels at 35 mg/L may be indicative of a preference for slight turbidity, as it may allow cover from predators or increase prey contrast. Juvenile yellow perch did not demonstrate a significant relationship between sediment concentration and circulating glucose, and the pooled mean level was 8.4 ± 0.4 mmol/L.

Primary Author:
Lisa Bowron
University of New Brunswick
Saint John, NB
[email protected]

Title: Exploring the effects on white sucker (Catostomus commersoni) during pulp mill closure and restart

The impacts of pulp mills effluents on fish and fish habitat have been studied at Jackfish Bay, Lake Superior, Ontario, Canada since the late 1980’s. Jackfish Bay has received the effluent from a large bleached kraft pulp mill (BKM) in Terrace Bay, ON since 1948. The site is isolated from other sources of contamination, industrial or municipal effluents. Ongoing studies conducted since 1988, showed that white sucker (Catostomus commersoni) had a number of reproductive alterations, including delayed maturity, decreased gonadal size, decreased expression of secondary sexual characteristics, and depressed levels of circulating steroids. Reductions in gonad size and steroid levels persisted until the pulp mill closed its hardwood line in the late fall of 2005, and ceased all effluent discharge from its softwood line from February 2006 to September 2006. Fish were collected in the spring and fall of 2006 during shutdown, and then again 8 months after the mill reopened. Relative to their performance as measured with the previous 17 years of data, males recovered quickly after mill closure, as did steroid hormone levels in females. Persistent whole organism responses in females may be related to a time lag associated with recovery of their egg production. Continued studies will evaluate these questions.

Primary Author:
Jennifer R. Adams
University of New Brunswick, Canadian Rivers Institute
Saint John, NB
[email protected]

Contributors:
Deborah L. MacLatchy and Kelly R. Munkittrick

Title: Fish reactions to exposure in oil refinery effluent and sediment in the laboratory and field.

Examination of the potential toxicity of oil refinery effluent at the refinery in Saint John, New Brunswick, Canada has continued since 2002. The refinery is the largest in Canada, producing 270 000 barrels or oil/day and discharges 24 274 m3/day. Initial work found complications involving low dissolved oxygen content in the receiving environment, Little River, due to discharged ballast water mixed in with treatment effluent. The current study began in 2006 with investigations in the laboratory and in the field after ballast water was removed from the effluent. Laboratory experiments utilized bioassays with two resident fish species, mummichog (Fundulus heteroclitus, a brackish water fish) and northern redbelly dace (Chrosomus eos, a freshwater fish), exposed to effluent or effluent with river sediments. Field experiments included a fish community survey, water quality survey and fish caging experiments with mummichog and dace. Caging experimental results in mummichog indicated increased liver size and liversomatic index (LSI) downstream of the effluent outfall in both 2006 and 2007. Female testosterone levels were elevated and condition in both sexes was decreased downstream. Laboratory experiments have not indicated similar effects. A possible explanation for the difference is continued low dissolved oxygen in the river during the summer months, during field experiments, that have not been simulated in the laboratory.

Primary Author:
Leslie Carroll
University of New Brunswick, Canadian Rivers Institute
Saint John, NB
[email protected]

Title: The reproductive biology of northern redbelly dace (Phoxinus eos) and their restricted use as a sentinel species for environmental effects monitoring programs

Several small-bodied cyprinid fishes have been proven to be well suited for use as sentinel species in environmental effects monitoring programs. However, insufficient information on life history characteristics, reproductive strategy, mobility, longevity, and food habitats for a number of species challenges the design of studies and restricts the interpretability. Several cyprinid species spawn multiple times throughout the summer, and seasonal variability in the relationships between gonad and body weights can influence the detection of differences in reproductive performance. Past studies have established that Northern Redbelly Dace (Phoxinus eos) exhibit high variability in gonad weight: body weight relationships during the spawning season. The objective of this study was to follow seasonal changes in condition, liversomatic index, gonadosomatic index and ovarian histology to examine the reasons for gonad development variability among female redbelly dace. Fish were collected monthly from two lakes within Rockwood Park, NB from August 2005 to August 2006. Gonad development happened very quickly in both males and females prior to spawning, there appeared to be little synchrony between fish and gonad weight: body weight regressions were not significant for 8 months of the year, including all spawning months. As many as four clutches of eggs were observed within the ovaries of female redbelly dace during May, June, July and August suggesting that they spawn at least 7 to 10 times during the summer. While variability in some cyprinid species can be reduced by restricting sampling to specific times, or certain sizes or ages, it appears that there is no simple way to reduce the variability among northern redbelly dace to improve their utility as a monitoring species.

POSTERS:

Primary Author:
Mark Gautreau
Canadian Rivers Institute
Fredericton, NB
[email protected]

Contributors:
R. Allen Curry

Title: Ecology of the Redbreast Sunfish Lepomis Auritus in Yoho Lake, New Brunswick

In Canada, the redbreast sunfish, Lepomis auritus, is only located in south western New Brunswick which is the northern limit of the species. In 1989, The Committee on the Status of Endangered Wildlife in Canada (COSEWIC), listed it as a species of concern due to its limited distribution. In 2005, the New Brunswick Cooperative Fish and Wildlife Research Unit, was commissioned by COSEWIC, to provide an updated status report on the redbreast sunfish. During this process it became apparent that there was a void in data on Canadian populations of redbreast sunfish, making an appropriate assessment difficult. The purpose of this research is to begin to build an ecological data base for the redbreast sunfish in New Brunswick. Snorkeling surveys were conducted during spawning to assess habitat use during spawning. Nests averaged 51.1 cm in diameter and average depth of 46.5 cm. Nest substrate was sandy with small gravel and 41 % of the nests observed were associated with some structure. Mark recapture sampling was carried out using fyke nets and windemere traps. The average total length and weight were 12.6 cm and 43.4 g respectively. The population estimate for 2006 was 447 individuals. The length frequency distributions were consistent over years and seasons. Overall the population of redbreast sunfish in Yoho Lake appears to be healthy and stable.

Primary Author:
Allen Curry
Canadian Rivers Institute
Fredericton, NB
[email protected]

Title: Maternal Transfer of Carbon and Nitrogen to Progeny of Sea-Run & Resident Brook Charr

Early-life history characteristics of sea-run and resident salmonid fishes that co-exist in sympatry are poorly understood. To assess differences in characteristics of offspring of these two strategies following their emergence to the stream, stable isotope ratios (d13C and d15N) were used to identify the progeny of resident and sea-run female brook charr (Salvelinus fontinalis) in a tributary of the Miramichi River, New Brunswick, Canada. Upon emergence, sea-run progeny captured in emergence traps were longer, heavier, and had higher carbon to nitrogen ratios (C/N, an indicator of lipid content) than resident progeny, but did not have a higher body condition. After some feeding and growth in the stream, sea run progeny (still identifiable by their d13C and d15N) captured in dip-nets became longer, heavier, had higher C/N, and had higher condition than resident progeny. The proportion of fish caught in dip-nets at 11 sites where the two forms co-existed was dominated by offspring of sea-run females (sea-run = 56%, resident = 19%, unknown = 25%). These analyses suggest that offspring of sea-run, female charr benefit from maternally-derived energy reserves gained at sea and thus have potential adaptive advantages over offspring of residents.

Primary Author:
Cindy Breau
Canadian Rivers Institute
Fredericton, NB
[email protected]

Title: Behaviour at high temperatures: can physiology explain movement of juvenile Atlantic salmon (Salmo salar) to cool water?

During the summer, wild salmonids experience water temperatures that approach their upper lethal limit. In the Little Southwest Miramichi River (NB, Canada), juvenile Atlantic salmon of different age classes exhibit different behavioural responses to high temperatures (>23ºC). Yearling (1+) and two-year (2+) old salmon cease feeding, abandon territorial behaviour, and swim continuously in aggregations near cool water refugia; however, young-of-the-year (0+) fish continue to feed and defend territories. A laboratory experiment was conducted to determine 1) if the behavioural shift in older juvenile salmon occurs when basal metabolic rate, driven by increasing water temperature, approaches maximum metabolic rate; and 2) if anaerobic pathways were being recruited to provide energy to support vital processes. Behaviour (feeding, startle response), oxygen consumption, circulating lactate and glucose levels, and muscle lactate and glycogen were measured in fish acclimated to temperatures between 16 and 28ºC. Results indicate that oxygen consumption of the 2+ salmon increased with temperature and reached a plateau at 24ºC, a temperature that also corresponded to a significant increase in lactate levels and cessation of feeding. In contrast, oxygen consumption in 0+ fish did not plateau, feeding continued and lactate did not increase, even at the highest temperatures tested. We therefore conclude that some behavioural responses of 2+ salmon to temperature stress may be employed in an effort to mitigate the physiological imbalances associated with an inability to aerobically support basal metabolism.

Primary Author:
Katrina Chu
Canadian Rivers Institute, University of New Brunswick
Fredericton, NB
[email protected]

Title: Examining the Importance of Marine-Derived Nutrients to Freshwater Stream Productivity within the Inner Bay of Fundy

Overall productivity in the rivers within the Inner Bay of Fundy has been notably declining over the past several decades. Anthropogenic influences within the region have been primarily targeted as the reason for the decline of economically viable species, such as Atlantic salmon (Salmo salar). The decrease in upper trophic level species, however, may be due to an overall decrease in primary productivity that stems from the decreasing numbers of anadromous fish that migrate from nutrient-rich marine environments into these freshwater systems. Anadromous species, such as rainbow smelt (Osmerus mordax) and alewife (Alosa pseudoharengus), are born in freshwater, migrate to the sea and return inland to spawn, bringing with them marine-derived nutrients (MDN) that could potentially enrich the streams through which they travel. Declines in the amount of MDN in a stream system could lower primary productivity, thus, decreasing benthic marcroinvertebrate populations as well as the likelihood of juvenile fish survival and adult returns. This negative feedback loop would only continue to decrease productivity within streams. This study will evaluate the importance of MDN to stream productivity by: i) analyzing historical catch data to estimate the extent of marine-derived nutrients in Maritime rivers and; ii) determine whether artificial fertilization as a proxy for MDN is feasible as a means to increase and promote Inner Bay of Fundy fish populations.

Primary Author:
Brianna Wyn
University of New Brunswick, Canadian Rivers Institute
Saint John, NB
[email protected]

Title: Factors Affecting Mercury Concentrations In Fish From Acidified Food Webs In Kejimkujik National Park, Nova Scotia

Although fish from low pH lakes are known to have high mercury (Hg), it is not known if processes such as food web length or atypically high biomagnification contribute to these high concentrations. This study has two main objectives: 1) characterize the food webs of four acidic (pH< 6) lakes in Kejimkujik National Park, Nova Scotia to assess whether trophic structure and Hg biomagnification are enhanced in acidic systems; 2) revisit lakes sampled in the mid-1990s to determine whether Hg in yellow perch has decreased over the past decade. Invertebrates and yellow perch, golden shiner, and banded killifish were captured in 2006 from four food web lakes. Yellow perch and golden shiner were also caught in 6 additional lakes for temporal comparisons. Stable carbon and nitrogen isotopes and total Hg were measured to compare food web structures among lakes and to contrast against the mid-1990 Hg concentrations. Results from the abovementioned analyses will be presented and discussed.

Primary Author:
Tim Jardine
Canadian Rivers Institute
Fredericton, NB
[email protected]

Title: Are coal-fired power plants affecting mercury concentrations in organisms in nearby streams?

Coal-fired power plants are known to be significant sources of mercury (Hg) to the surrounding region. However, the possibility of enhanced bioaccumulation of Hg through stream food webs due to this localized deposition has rarely been examined, despite the potential risks to nearby aquatic populations. In 2006 we examined deposition of Hg onto the terrestrial landscape and its bioaccumulation through stream food webs by collecting the lichen Old Man’s Beard (Usnea sp.), benthic invertebrates, and fishes in a bulls-eye design at increasing distances away from a coalfired power plant in New Brunswick, Canada. Samples were analyzed for total Hg and stables isotopes of nitrogen (d15N) to determine trophic positioning. The terrestrial sentinel Old Man’s Beard indicated enhanced mercury deposition within 10 km of the plant and significantly elevated concentrations as far away as 100 km. Biomagnification of Hg within streams, as measured by slopes of the Hg-d15N relationships for invertebrates and fishes, was higher at sites near the power plant, and differences in the biomagnification of this pollutant also depended on the fish species present. Blacknose dace had higher mercury concentrations than brook trout leading to greater Hg-d15N slopes in streams containing only the former species. Biomagnification of Hg was also linked to water chemistry; acidic streams with high organic matter content showed greater slopes of Hg versus d15N. Future analyses will focus on separating the relative importance of water chemistry and the point source in the accumulation of Hg through these food webs to determine if the power plant may be negatively impacting aquatic populations and fisheating consumers including humans.

Primary Author:
Rosalyn Smedley
Canadian Rivers Institute, Department of Biology, University of New Brunswick
Fredericton, NB
[email protected]

Contributors:
R.A. Curry, J.Culp, and M. Gray

Title: Stream and catchment scale effects on fish condition and community composition in an agricultural landscape

Agricultural land-use can cause significant sediment input into adjacent streams. The severity of effects of suspended sediment input on fish has been modeled for southern USA streams based on duration and intensity of the sediment event, i.e., suspended sediment where effects is scored from no impact to mortality of fishes. The project will test the severity of ill-effects (SEV) impact assessment model in northern New Brunswick, a region comprising Canada’s third largest potato production region. Sixteen sites comprising a gradient of agricultural impact are being used to assess stream and catchment scale effects on fish. Environmental variables, such as suspended sediment levels, were collected throughout the agricultural season while electrofishing surveys were conducted in the late summer. The relationship between fish condition and environmental variables is explored to determine the most significant impact on health and community composition. Preliminary work found lower fish abundance in streams within the most intense potato production. Continuing research will establish the link between SEV, suspended sediment loading and other increased pressures from agriculture and the impacts on fish in Canadian waters