John M. Farrell

Reproductive Success of Sympatric Northern Pike and Muskellunge in an Upper St. Lawrence River Bay

Abstract A change in the use of spawning habitats linked with water-level management may explain differences in reproductive success among sympatric St. Lawrence River northern pike Esox lucius and muskellunge Esox masquinongy. Reproductive success in a shared spawning and nursery bay was compared based on egg (embryo) and age-0 abundance estimates before the fall emigration of young. Historically, northern pike were noted to commence spawning runs in shallow flooded areas soon after ice-out. I found that more than 87% of the estimated northern pike egg deposition in 1994 occurred in offshore, deep-water habitats (2–5 m) and that 99% did in 1995. Northern pike began spawning 17 d before muskellunge in 1994 and 31 d earlier in 1995. Spawning peaks occurred during the interval of 16–23 May. Muskellunge mostly spawned near shore (<1.5-m depth) in submerged aquatic vegetation growth that was absent during northern pike spawning. Muskellunge spawning began and peaked between 23 May and 4 June in 1994 and betwe...

Notes: Egg Distribution and Spawning Habitat of Northern Pike and Muskellunge in a St. Lawrence River Marsh, New York

Abstract Coexistence of northern pike Esox lucius and muskellunge Esox masquinongy in the Niagara and St. Lawrence rivers has been hypothesized to depend on segregation during spawning. However, large overlap in the use of spawning areas by these two species occurs in the Thousand Islands section of the upper St. Lawrence River. In this study, egg collections in Point Marguerite Marsh in the upper river revealed a partial temporal and spatial overlap in egg deposition by northern pike and muskellunge. Northern pike began spawning earlier but overlapped with muskellunge spawning for 2 weeks, May 13–27. Northern pike eggs were collected over a larger area than muskellunge eggs and at all locations where muskellunge eggs were collected. Both species deposited eggs over three dominant genera of vegetation: pondweeds Potamogeton, duckweeds Lemna, and stonewort Chara. Northern pike spawned over a wider range of water depths (0.5–2.6 m) than muskellunge (0.8–1.5 m) and selected habitats with denser, taller veget...

Distribution, Abundance, and Survival of Age-0 Muskellunge in Upper St. Lawrence River Nursery Bays

Abstract Distribution, abundance, and survival of age-0 muskellunge Esox masquinongy were evaluated at 10 bays in the Thousand Islands section of the St. Lawrence River over a 7-year period, 1990–1996. Muskellunge fry (24 mm) identified with thermal or oxytetracycline otolith markers were stocked in 1990–1992, 1994, and 1996, and fin-clipped fingerlings (76 mm) were stocked in the bays in 1994 and 1996. Success of the stockings was evaluated to examine the feasibility of enhancing bays that have natural reproduction (natural) and establishing populations in unused bays (restoration). Most age-0 muskellunge were found in shallow habitats (<1.5 m), and success of capture by seining decreased with increasing water depth. Estimates of age-0 abundance by mark–recapture and catch–area were not significantly different. Population density ranged from 0 to 42 muskellunge/ha of nursery habitat, and no significant differences were observed between natural (18.8 fish/ha) and restoration bays (20.5 fish/ha). For all y...

Quantification of native muskellunge nursery habitat: influence of body size, fish community composition, and vegetation structure

Habitat utilization of native young-of-the-year (YOY) muskellunge, Esox masquinongy, was quantified by the type and density of vegetation present, water depth, and fish communities associated with their presence and abundance in nursery bays of the Upper St. Lawrence River. We completed 441 seine hauls and captured 400 YOY muskellunge in 11 bays that were sampled each July and August over a 3-year period (2002–2004). We hypothesized a change in habitat utilization related to increasing body size, as YOY muskellunge doubled in total length from July to August. Fine-leafed submerged and emergent macrophytes and prey availability (cyprinids, Notropis sp., banded killifish, Fundulus diaphanous and tessellated darter, Etheostoma olmstedi), were positively related to muskellunge use in July, while in August coverage of broad-leafed submerged macrophytes and increased overall vegetation density were the best habitat descriptor. In both months, muskellunge were associated with moderate (20–60%) vegetation coverage and density, however, captures were in areas of significantly greater vegetation coverage and density than was generally available. A negative relation of muskellunge occurrence with water depth, yellow perch, Perca flavescens, and stonewort, Chara vulgaris, was observed in both months. The negative relationship between muskellunge and depth, plus their strong linkages to nearshore submerged vegetation and forage fish that inhabit the nearshore areas, highlights the importance of protecting the ecological integrity of nearshore habitats. Our findings should assist managers in protecting native stocks, planning restoration and enhancement initiatives, and in regulating riparian and nearshore development.

Potential effects of spawning habitat changes on the segregation of northern pike (Esox lucius) and muskellunge (E. masquinongy) in the Upper St. Lawrence River

Changes in spawning habitat of northern pike (Esox lucius) may affect their segregation from and coexistence with the closely related muskellunge (E. masquinongy). We estimated the areal coverage of robust and shallow emergent vegetation in three shared-spawning bays in the Upper St. Lawrence River from aerial photographs taken from 1948 to 2003. Robust emergent vegetation (e.g., cattail) increased in coverage by 155–241% while shallow emergents (sedges) decreased by 46–96%. The loss of sedges, an important northern pike-spawning habitat, may facilitate greater spawning overlap in offshore-submersed aquatic vegetation within bay habitats used by muskellunge. Development rates and characteristics of northern pike and muskellunge eggs and larvae were compared to better understand the implications of greater spawning overlap. Northern pike eggs developed faster than muskellunge eggs at temperatures of 4.7–19°C, and adhesive eggs and the presence of adhesive papillae were present in both species. Equations were used to predict degree-day requirements for hatching and swim-up in three habitats (shallow emergents, bay, and offshore shoal) along a temperature gradient. Northern pike required more estimated degree days to reach hatching in bay and offshore shoal habitat relative to shallow emergent habitat due to cooler temperatures. Significant spawning overlap is known to occur within bay habitats, but poor success of northern pike in deep bay habitats and overall reductions in abundance are hypothesized to currently buffer muskellunge from potential negative interactions between these species.

Holocene vegetation dynamics of an upper St. Lawrence River wetland: paleoecological evidence for a recent increase in cattail (Typha).

Cattails (Typha latifolia L., Typha angustifolia L., and Typha x glauca Godr.) are the predominant emergent vegetation of upper St. Lawrence River coastal wetlands. We sought to describe Holocene vegetation in a St. Lawrence River wetland to assess patterns of succession and examine the timing and potential causes of a historic cattail invasion. Paleoecological analysis indicated presence of four distinct wetland vegetation stages, including a shallow water marsh (8240 YBP to 5160 YBP), a variable-depth aquatic plant community with adjacent alder (5160 YBP to 1610 YBP), a shallow sedge community (1610 YBP to 100 YBP), and a robust emergent marsh (100 YBP to present). The record of pollen tetrads demonstrated cattail presence throughout the history of the marsh, but a rapid increase in relative abundance of Typha cf. angustifolia/Sparganium monads indicated major expansion of robust emergent plants beginning near the peak of agricultural activity (ca. 1880 AD) and reaching modern levels around 1940 AD. Increase in the abundance of robust emergents in this wetland occurred decades before regulation of St. Lawrence River water levels and were contemporary with increased sedimentation and changes associated with the early agricultural period.

Temporal Variation in Prevalence of Viral Hemorrhagic Septicemia Virus Type IVb among Upper St. Lawrence River Smallmouth Bass

Abstract We investigated a newly introduced pathogen in a wild population of smallmouth bass Micropterus dolomieu in the St. Lawrence River to illuminate unknown temporal and demographic prevalence patterns. We used real-time quantitative reverse-transcription polymerase chain reaction to assess viral hemorrhagic septicemia virus (VHSV) genotype IVb (VHSV-IVb) viral N-gene levels. Our objectives were to characterize the distribution and abundance of this newly introduced pathogen within a naive population of economically valuable sport fish through an annual cycle. We also sought to describe VHSV-IVb levels across demographic groups (males and females; adults and subadults). Strong temporal variation in prevalence of VHSV-IVb was evident through the annual cycle; peaks in prevalence corresponded to the smallmouth bass spawning period and a temperature range of 10–14°C. No difference in VHSV-IVb prevalence between male and female smallmouth bass was detected. However, a markedly higher prevalence was obser...

Year-Class Formation of Upper St. Lawrence River Northern Pike

Abstract Variables associated with year-class formation in upper St. Lawrence River northern pike Esox lucius were examined to explore population trends. A partial least-squares (PLS) regression model (PLS 1) was used to relate a year-class strength index (YCSI; 1974–1997) to explanatory variables associated with spawning and nursery areas (seasonal water level and temperature and their variability, number of ice days, and last day of ice presence). A second model (PLS 2) incorporated four additional ecological variables: potential predators (abundance of double-crested cormorants Phalacrocorax auritus and yellow perch Perca flavescens), female northern pike biomass (as a measure of stock–recruitment effects), and total phosphorus (productivity). Trends in adult northern pike catch revealed a decline (1981–2005), and year-class strength was positively related to catch per unit effort (CPUE; R 2 = 0.58). The YCSI exceeded the 23-year mean in only 2 of the last 10 years. Cyclic patterns in the YCSI time ser...

Muskellunge and Northern Pike Ecology and Management: Important Issues and Research Needs

New research techniques and changing Muskellunge Esox masquinongy and Northern Pike E. lucius fisheries have contributed to paradigm shifts in the science and management of these species. A symposium on Muskellunge and Northern Pike biology, ecology and management was held at the American Fisheries Society Annual Meeting in Little Rock, Arkansas, and a panel discussion following the symposium identified several research and management priorities, including spawning habitat identification, habitat and population restoration, genetics, and selective mortality and exploitation. Future Muskellunge and Northern Pike research should focus on quantifying egg and age-0 survival based on habitat characteristics, rigorously evaluating habitat restoration efforts using statistically sound study designs, describing range-wide genetic structure of populations, and developing a better understanding of how selective mortality and exploitation can alter population size structure, sex ratios, and life history characterist...

Feeding patterns and population structure of an invasive cyprinid, the rudd Scardinius erythrophthalmus (Cypriniformes, Cyprinidae), in Buffalo Harbor (Lake Erie) and the upper Niagara River

Feeding patterns and population structure of the non-native rudd Scardinius erythrophthalmus (Linnaeus) were examined to understand their ecology in Buffalo Harbor and the Niagara River. We hypothesized that (1) the diet of rudds would be omnivorous, but contain greater proportions of macrophytes in summer months, (2) feeding intensity would increase with water temperature, and (3) condition and growth would be similar to other populations. We collected rudds with a variety of gears in 2009 to test these hypotheses, and used data from 2007 to 2010 seining surveys to determine if the relative abundance of young-of-the-year rudd differed among sites with different flow conditions. Rudds were mostly herbivorous; they consumed aquatic macrophytes in summer and supplemented their diet with algae and fish in spring and fall. Feeding intensity was positively correlated with water temperature, but significantly reduced during spawning. Rudd condition and growth were greater than estimates from other populations, suggesting increases in abundance and range expansion are possible. Furthermore, reproduction was successful at lotic sites but very poor at sites without measureable flow, contrary to the paradigm of optimal rudd habitat. Research is needed to understand how herbivory by abundant rudd populations affects native aquatic communities.