Population biology and fishery characteristics of the smooth-hound Mustelus schmitti in Anegada Bay, Argentina

Age and growth of the highly exploited narrownose smooth-hound (Mustelus schmitti) (Pisces: Elasmobranchii)

“…The narrownose smooth-hound of Anegada Bay has a relatively fast growth in its initial year of life, reaching a length of approximately 400 mm TL. Growth slows down in subsequent years, and, according to our results, length at first maturity (546 and 563 mm TL for males and females respectively; Colautti et al, 2010) is reached at an age of 7.61 years for females and 6.79 years for males. These values represent a maturation rate comparable to that of other species of Mustelus; for example, the eastern spotted gummy shark matures at an age around 7-9 years and at a length of 670 to 800 mm TL (Rigby et al, 2016).…”

“…The age of each individual fish was determined by the number of translucent bands, the date of capture, and the date of birth, which was assumed to be 1 January. This assumption is supported by the fact that a high proportion of gravid females were captured in a previous sampling campaign in December 2007 and by the high number of young of the year captured in February 2008 (Colautti et al, 2010). For example, a fish that was captured on 12 February 2008 and had 2 bands was calculated to have an age of 408 d (1.12 years).…”

“…This shark is known to migrate seasonally, in large numbers, between wintering grounds in southern Brazil and summering grounds in Argentina (Figueiredo, 1977;Vooren, 1997). Seasonally, it also frequents estuaries, protected bays, and gulfs (Lopez Cazorla, 1987;Chiaramonte and Pettovello, 2000;Colautti et al, 2010;Molina, 2013).…”

“…The narrownose smooth-hound is one of the most studied sharks of Argentina: several scientific publications describe its reproduction, food habits, and other aspects of its biology (Menni, 1985;Menni et al, 1986;Cousseau et al 4 ;Chiaramonte and Pettovello, 2000;Sidders et al, 2005;Cortés and Massa 5 ;Segura and Milessi, 2009;Colautti et al, 2010;Molina and Lopez Cazorla, 2011 that deal with this aspect. Science-based studies on age and growth are crucially important for research of population dynamics because, without accurate age and growth estimations, it is impossible to perform adequate fisheries stock assessments, make accurate forecasts, and provide effective management (Chugunova, 1963;Reeves, 2003;Methot and Wetzel, 2013).…”

A trans-ecosystem fishery: Environmental effects on the small-scale gillnet fishery along the Río de la Plata boundary

“…Although both fisheries captured the same coastal fish assemblage (Jaureguizar et al, 2006b;Llompart et al, 2013) and used the same net (90e120 mm), the RdP gillnet fishery landings were mostly based on Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Parona signata, which represented 93% of spring landings composition, while in the San Blass gillnet fishery 96% of spring landings consisted of M. schmitti. This difference can be related to the high aggregation of this small shark during its mating and reproduction time, when adults enter the bay during spring and remain until the summer (Colautti et al, 2010). The RdP gillnet fishery also showed significant decadal differences in the species composition of the landings.…”