Expulsion of miniature radio transmitters along with eggs of muskellunge and northern pike––a new method for locating critical spawning habitat

Abstract

Identification and protection of critical spawning habitat for muskellunge Esox masquinongy and northern pike Esox lucius is important for preserving the reproductive potential of both species. In this study, we implanted miniature radio transmitters through the oviduct into the egg masses of female muskellunge and northern pike just prior to spawning. This non-surgical procedure was a novel approach for identifying spawning sites when transmitters were expelled with the eggs during egg deposition. Preliminary studies in three lakes showed that muskellunge and northern pike deposited many of the transmitters in likely spawning habitat. An inability to find eggs limited our validation of this method, but nevertheless, a relatively high proportion (70%) of northern pike larger than 690 mm (27.2 inches) expelled transmitters in a previously known spawning area in Willow Lake, Minnesota. Shoreline vegetation in that area consisted primarily of sedges Carex spp., and the adjacent water was shallow with substrate consisting of large mats of water bulrush Scirpus subterminalis. A lower proportion (50%) of muskellunge expelled transmitters in Elk Lake, Minnesota. Water depth at likely spawning sites averaged 1.1 m (3.6 feet) and vegetative cover was variable, but Chara spp. was common to most sites. In Moose Lake, Minnesota, containing sympatric populations of muskellunge and northern pike, 60% of muskellunge and 90% of pike expelled transmitters. Chara spp. beds were the predominant substrate where transmitters were expelled in Moose Lake, but the two species deposited transmitters on deepwater bars (3.7-5.2 m) in addition to shallow near-shore habitat. These results suggest more flexibility in depths used for spawning than typically reported for muskellunge and northern pike.

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

“…A weakness of this method is that it can be used only in shallow areas, so it may miss spawning in deeper water; maximum depth for visual observation during spotlight surveys is generally 1.0-2.0 m (Zorn et al 1998;Crane et al 2014;Nohner and Diana 2015). Implanting minitransmitters in oviducts of mature females and then locating transmitters once they are expelled during spawning is another technique used to identify spawning habitats of both species (Pierce et al 2007;Battige 2011). This method should be coupled with collection of fertilized eggs to confirm that the transmitter was expelled during the spawning process.…”

Short‐Term Passive Integrated Transponder Tag Retention in Wild Populations of Bluehead and Flannelmouth Suckers

“…Laboratory and caged studies also fail to account for natural behaviors such as spawning. Tags inserted into the abdomen of gravid fish can be expelled with eggs during spawning, but studies directly addressing short-term tag retention during spawning have been limited to very few fish species, such as Rainbow Trout Oncorhynchus mykiss, Brown Trout Salmo trutta, Brook Trout Salvelinus fontinalis, and Largemouth Bass Micropterus salmoides (Harvey and Campbell 1989;Pierce et al 2005;Bateman et al 2009;Dieterman and Hoxmeier 2009;Meyer et al 2011).…”

Reproductive ecology of muskellunge (Esox masquinongy), an introduced predator, in the lower Wolastoq/Saint John River, New Brunswick, Canada

“…By combining both methods to visually identify spawning pairs we were able to identify the location of spawning habitat downstream of Mactaquac Dam. Muskellunge are known for their reproductive plasticity and are capable of spawning over a variety of substrates from mud to cobble (Dombeck et al ., 1984; Nohner, 2009; Younk et al ., 1996) and at water depths from <1 m (Battige, 2011; Younk et al ., 1996) to 2–3 m (Pierce et al ., 2007; Strand, 1986), therefore relatively few assumptions could be made on potential spawning sites solely based on available habitat. While deep‐water spawning seems anomalous amongst most muskellunge populations, the lack of data may be a function of difficulties relating to making effective observations at greater depths.…”

“…Our habitat sampling was the first successful attempt at describing the micro‐habitat characteristics of muskellunge spawning habitat in the Wolastoq/Saint John River. Spawning and nursery habitat parameters were consistent with those reported in other studies (Crane et al ., 2014; Farrell et al ., 1996; Pierce et al ., 2007; Rust et al ., 2002; Strand, 1986; Warren, 2013; Zorn et al ., 1998), with the exception of higher than normal DO values. As Farmer and Chow‐Fraser (2004) explain with their conceptual model of muskellunge spawning habitat, the primary drivers of successful spawning ( i.e ., water temperature, DO and egg separation) are mostly influenced by secondary variables ( e.g ., depth, velocity and substrate particle size).…”

“…Despite these general habitat requirements, muskellunge exhibit significant plasticity in spawning habitat selection (Diana et al ., 2017). Muskellunge may spawn in deeper water (>1 m) over a variety of substrates (Crane et al ., 2014; Farrell et al ., 1996; Pierce et al ., 2007; Strand, 1986) and in some cases at temperatures ranging from 6 to 7°C (Nohner, 2009; Zorn et al ., 1998). Muskellunge have high spawning site fidelity and are fractional spawners, waiting days to weeks after the initial spawning event to spawn again (Gillis et al ., 2010).…”