Sharks and rays are widely perceived to have slow reproductive rates and, thus, are often considered highly susceptible to population declines from commercial fishing. However, the reproductive biology of sharks is highly diverse, and some species can sustainably support significant commercial harvest. Small sharks are commonly caught and discarded as bycatch in several Australian and international fisheries. This represents either a wasted resource that could potentially be sustainably utilised, or a potential conservation issue if overharvesting occurs. This study examines the reproductive biology of two small-bodied sharks in the Northern Territory, Australia. Carcharhinus coatesi (n = 726) and Rhizoprionodon acutus (n = 179) were collected between May 2018 and November 2019 from commercial trawl fisheries. Maximum lengths in both species were higher in females than males (C. coatesi: F = 862 mm, M = 822 mm; R. acutus: F = 862 mm, M = 835 mm). Size at 50% maturation size C. coatesi: F = 655 mm, M = 664 mm; R. acutus: F = 682 mm. Size-at-maturity that the logistic model predicted for male R. acutus (715 mm) appears to represent size at full maturation and this study could not determine 50% maturation size. Litter sizes were small in both species, with C. coatesi producing 1–2 pups (mean 1.9) and R. acutus producing 1–4 pups (mean 2.8). Both species gave birth to large pups when compared to other shark species (C. coatesi: 370 - 450 mm; R. acutus: 315 – 400 mm), with C. coatesi size-at-birth being 47.6% of maximum female total length, while R. acutus size-at-birth was 41.5% of maximum female total length). Both species reproduced throughout the year, complicating estimation of the gestation period. The reproductive biology of C. coatesi and R. acutus showed considerable spatial and temporal variability when compared to studies from other regions and a past study from the Northern Territory in 1991. Although C. coatesi and R. acutus are currently abundant in the Northern Territory, the low fecundity of both species compared to other small-bodied sharks may limit their potential to sustain high levels of commercial harvest. Any expansion of commercial fishing for these species should be based on detailed consideration of their reproductive biology—in particular their low fecundity—to avoid the declines experienced by other formerly abundant elasmobranchs globally.

人们普遍认为鲨鱼和鳐鱼的繁殖速度较慢，因此通常被认为极易受到商业捕捞造成的种群数量下降的影响。然而，鲨鱼的繁殖生物学高度多样化，有些物种可以持续支持大量的商业捕捞。在一些澳大利亚和国际渔业中，小鲨鱼通常被作为副渔获物捕获并丢弃。这要么代表着一种可能可持续利用的资源浪费，要么代表着过度采伐时潜在的保护问题。这项研究调查了澳大利亚北领地两种小型鲨鱼的生殖生物学。2018 年 5 月至 2019 年 11 月期间，从商业拖网渔业中收集了Carcharhinus cotesi（n = 726）和Rhizoprionodon acutus （n = 179）。两个物种的最大长度雌性均高于雄性（C. cootesi：F = 862 mm，M = 822 mm；R. acutus：F = 862 mm，M = 835 mm）。50% 成熟尺寸C.coatesi：F = 655 mm，M = 664 mm；R. acutus：F = 682 毫米。逻辑模型预测的雄性尖头犀（715 毫米）的成熟尺寸似乎代表了完全成熟时的尺寸，而本研究无法确定 50% 成熟尺寸。两个物种的产仔数都很小，C. cotesi产仔 1-2 只（平均 1.9 只），R. acutus产仔 1-4 只（平均 2.8 只）。与其他鲨鱼物种相比，这两种鲨鱼都产下了较大的幼仔（C.coatesi：370 - 450 毫米；R. acutus：315 - 400 毫米），C.cotesi出生时的体型占雌性最大总长度的 47.6% ，而R. acutus出生时大小为最大雌性总长度的 41.5%）。这两个物种全年繁殖，使妊娠期的估计变得复杂。与其他地区的研究以及 1991 年北领地的一项研究相比，C.coatesi和R. acutus的繁殖生物学表现出相当大的空间和时间变异性。尽管C.coatesi和R.acutus目前在北领地数量丰富与其他小型鲨鱼相比，这两个物种的繁殖力较低，可能会限制它们维持高水平商业捕捞的潜力。对这些物种的商业捕捞的任何扩张都应基于对其繁殖生物学的详细考虑，特别是其低繁殖力，以避免全球其他以前丰富的软骨鱼类经历的衰退。