Great Lakes Fishery Commission

SLAP Phase II addresses a critical bottleneck in Great Lakes sea lamprey research: the declining availability of large larvae, transformers, and juveniles needed for experiments. Intensified lampricide control has reduced wild densities of collectable animals, while juveniles remain especially difficult to obtain because of low abundance, unpredictable migration timing, and inefficient capture. Phase I demonstrated that sea lamprey can be produced and reared at scale under laboratory conditions, including production of hundreds of thousands of embryos, tens of thousands of larvae, accelerated larval growth relative to wild populations, and likely production of hundreds of transformers. However, Phase I also revealed important differences between artificially propagated lab-reared larvae (APLR) and wild-caught lab-reared larvae (WCLR) in growth, physiology, body composition, and behavior, creating uncertainty about whether captive-reared animals are fully comparable to wild animals.\r\n\r\nThe central goal of Phase II is to determine whether APLR and WCLR sea lamprey can successfully complete metamorphosis, initiate parasitic feeding, grow on host fishes, and develop into biologically useful juveniles or adults. The proposal is organized around two major objectives: (1) determine how the morphology, physiology, gene expression, energetic condition, and timing of metamorphosis vary between wild-origin and laboratory-reared sea lamprey; and (2) determine how parasitic feeding behavior, somatic growth, thermal performance, stress physiology, exercise capacity, gut microbiome, and early juvenile physiology differ among wild-origin and laboratory-reared juveniles.\r\n\r\nThe research plan consists of 12 coordinated studies spanning a “genes-to-whole-organism” framework. Studies under Objective I examine metamorphic progression, energy stores, respiration and fuel use, and transcriptomic changes before, during, and after metamorphosis. Studies under Objective II examine juvenile feeding behavior and growth, hormonal stimulation of feeding, gut microbiome development, aerobic and anaerobic performance, stress response, artificial feeder development, and non-invasive approaches for tracking metamorphosis, sex determination, and sexual maturation. Together, these studies are designed to determine whether captive-reared sea lamprey are suitable experimental surrogates for wild animals and to identify the conditions necessary for reliable production of later life stages.\r\n\r\nThe work builds on substantial existing infrastructure at Hammond Bay Biological Station and in the SLAP mobile aquaculture trailer, including rack systems for larval rearing, embryo incubation tanks, juvenile/adult holding tanks, a large artificial stream, outdoor tanks, and temperature-controlled systems. \r\n\r\nExpected deliverables include a scalable captive-rearing pipeline capable of producing juvenile sea lamprey within approximately three years of fertilization; standardized husbandry protocols for larval-to-juvenile culture; an artificial feeder prototype and SOP; new datasets on metamorphosis, feeding, growth, physiology, microbiome dynamics, and gene expression; and molecular tools including RNA-seq resources, qPCR panels, and OpenArray gene chips for assessing growth, metabolism, stress, sex, and developmental state. The project will also train undergraduate students, graduate students, research associates, and technicians across multiple partner institutions.\r\n\r\nOverall, SLAP Phase II is both a fundamental biological study of sea lamprey metamorphosis and juvenile parasitism, and an applied platform for sea lamprey control research. By providing reliable, year-round access to large larvae, transformers, and juveniles, the project will ultimately reduce dependence on unpredictable wild collections, accelerate testing of pesticide refinements and behavioral or genetic control tools, and support more selective, adaptive, and biologically informed sea lamprey management in the Great Lakes.

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