The Great Lakes - St.Lawrence Research Inventory

Renibacterium salmoninarum (Rs) is the causative agent of bacterial kidney disease (BKD), a significant disease of Chinook salmon in the Great Lakes. Rs can cause a long-term persistent infection and infected fish may not necessarily show disease. The standard susceptible-infected-recovered (SIR) population framework for disease does not model Rs infection dynamics well. Fenichel et al. 2009 (Ecol. Apps V19:747) proposed a conceptual framework for Rs, which we have modified here as the ‘susceptible-latent-diseased-latent’ (SLDL) model.

Eel-ladder-style traps (ELST) – inclined ramps with vertical pegs and trickle flow- are a potential addition/alternative to traditional funnel traps for adult lamprey assessment and control. ELST have potential advantages over funnel traps in species selectivity, entrance rate of lamprey that encounter the traps, retention in the trap, safety of trap operation, and ease of baiting with pheromones. As an alternative sea lamprey trapping method, ELST could be used to test crucial assumptions of the adult lamprey assessment program, which relies on unbiased mark-recapture estimates.

Prior to widespread use of lampricides, thousands of transformed sea lamprey (Petromyzon marinus) were captured in nets and inclined screen traps by intercepting them during their downstream migration from autumn through spring. Nets and screen traps, while effective at capturing transformers, were vulnerable to debris and ice fowling, which greatly reduced efficiency unless serviced several times daily.

We question the specifics of the parasite-host interactions between sea lamprey and lake whitefish. The probability that an individual fish will survive an attack from a sea lamprey is a key component to sea lamprey damage assessments. Comprehensively studied for lake trout, survivability for whitefish is unclear with a single mark-recapture study from the 1960s providing data. Laboratory research has not been conducted to support or refute the results of the tagging study, which was completed when ecological conditions in the Great Lakes differed from those of today.

Great Lakes coastal embayments provide critical habitats for warmwater fishes, yet many have experienced severe habitat degradation. Millions of dollars are being spent on habitat restoration, yet biotic responses are poorly understood. An acoustic telemetry study is currently underway in Toronto Harbour, examining responses to habitat restoration by key warmwater (largemouth bass; Micropterus salmoides) and coolwater (northern pike; Essox lucius) predators, and invasive species (common carp; Cyprinus carpio).

The development of non-invasive technologies to divert adult sea lamprey migrations and direct adults into traps where physical barriers are not present is a primary research objective of the sea lamprey control program (McLaughlin et al. 2007). Traps have the potential to aid the control effort by removing pre-spawning phase animals from the population. However, only traps associated with barriers are currently effective, and even then, effectiveness varies widely among tributaries around the Great Lakes hindering utility of trapping as a control tool.

The development of non-invasive technologies to divert adult sea lamprey migrations and direct adults into traps where physical barriers are not present is a primary research objective of the sea lamprey control program (McLaughlin et al. 2007). Traps have the potential to aid the control effort by removing pre-spawning phase animals from the population. However, only traps associated with barriers are currently effective, and even then, effectiveness varies widely among tributaries around the Great Lakes hindering utility of trapping as a control tool.

RATIONALE: Trapping as a component of sea lamprey control is only effective at barriers to sea lamprey migration. In streams without barriers, an approach is needed that draws animals to the device (e.g. pheromones) or repels and crowds them to one side of a river for trapping (e.g. electrical barrier). A fish guidance system named NEPTUN developed by Procom Systems in Poland has been effective in using vertical electrodes and random patterns of pulsed-DC current at power dams to repel fish.