Efficacy of Spawning Alligator Gars in Recreational‐Grade Swimming Pools

Abstract

Alligator Gar Atractosteus spatula numbers have declined throughout much of the species’ historic range due to anthropogenic effects (habitat alteration or loss, commercial fishing, and recreational fishing). As a result, many conservation agencies now rely on hatchery production of Alligator Gars to aid in recovery and reintroduction efforts. Because of difficulty in harvesting juvenile Alligator Gars from hatchery ponds, we evaluated the use of recreational‐grade swimming pools (4.6 m in diameter × 1.2 m deep) for spawning Alligator Gars, as this may result in increased production and more efficient harvest of juveniles. In May 2018, two recreational‐grade swimming pools were used to successfully spawn Alligator Gars, producing a total of approximately 159,000 fingerlings. Recreational‐grade swimming pools provided an efficient, low‐cost environment for the spawning of Alligator Gars. Alligator Gar fingerlings can be harvested from these pools with near 100% efficiency. Furthermore, this method reduced the need to use multiple males per female during spawning because they are confined to a small spawning environment. The use of recreational‐grade swimming pools for the culture of Alligator Gars resulted in refinement and increased efficiency in spawning this species, thereby offering a technique that should enhance Alligator Gar restoration efforts by increasing hatchery production capabilities.

Modeling the Population Response of Alligator Gar in Texoma Reservoir to Harvest and Discard Mortality

“…2010; Stewart and Long 2015, 2016; Porta et al. 2019). For example, based on our age data, a dominant year‐class was produced every 9.25 years (the 1978, 2002, 2007, 2013, and 2015 year‐classes comprised 63% of the 152‐fish sample) and a year‐class contributing to the adult population was produced in 15 out of 43 years (on average, every 2.5 years).…”

“…2020) and following the year‐classes through time could be used by managers to identify noncontributing year‐classes and the need for working with hatcheries to offset sporadic recruitment (Porta et al. 2019). Additionally, a maintenance stocking can be used to offset the exploitation rate of 0.05 (120 individuals), which results in about 40 individuals being harvested annually until the next successful recruitment event.…”

Critical thermal minima of alligator gar ( Atractosteus spatula , [Lacépède, 1803]) during early life stages

“…In order to facilitate spawning, TNFH pulled adult alligator gar from holding ponds once water temperature reached 24°C. TNFH injected these gar with a LHRH (luteinizing hormone releasing hormone) analog and then placed them into recreational‐grade swimming pools (4.6 m in diameter × 1.2 m deep) that contained black willow ( Salix nigra , [Marshall, 1785]) branches as spawning substrate (Porta et al., 2019). Three days after hatching, we collected the juvenile alligator gar from TNFH and transported them to the Oklahoma Fisheries Research Lab.…”

“…Historically, populations occurred in the Mississippi River drainage basin from Illinois (USA) to Mexico (Ferrara, 2001; Fernando et al, 2016). However, throughout much of their range, alligator gar populations have been reduced or extirpated (Fernando et al., 2016; Ferrara, 2001; Porta et al., 2019). Leading contributors to alligator gar population decline include overexploitation and habitat degradation (Brinkman, 2008; Buckmeier, 2008; Scarnecchia, 1992; van der Most & Hudson, 2017).…”

“…In response to the decline of alligator gar populations, several conservation agencies have implemented stocking programs to reintroduce alligator gar into areas where they have been locally extirpated (Hilsabeck et al, 2017;Mendoza et al, 2002;Porta et al, 2019). These efforts have been aided by the recent elucidation of many ecological and life-history aspects of this species, including individual movements (Buckmeier et al, 2013;Militello, 2013;Solomon et al, 2013), early life history (Brinkman, 2008;Snow, Shoup, et al, 2018), recruitment success (Buckmeier et al, 2017;, development (Aguilera et al, 2002;Long et al, 2020;Mendoza et al, 2002), and critical thermal maxima (CT max ;Fernando et al, 2016).…”