Age and Growth of Stone Scorpionfish (Scorpaena Mystes) from the Gulf of California in Mexico
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324 National Marine Fisheries Service Fishery Bulletin First U.S. Commissioner established in 1881 of Fisheries and founder NOAA of Fishery Bulletin Abstract—The stone scorpionfish (Scor- Age and growth of stone scorpionfish paena mystes) is common throughout the Gulf of California in Mexico. Because (Scorpaena mystes) from the Gulf of little information is available regard- ing the basic biological characteristics California in Mexico of this species and because commercial demand for it is increasing, the need Ulianov Jakes-Cota (contact author)1 for studies of population dynamics is Arturo Tripp-Valdez1 urgent. We sampled 233 stone scorpi- 1 onfish (117 males and 116 females) in Marisol Arce-Acosta 2 the Gulf of California from May 2015 Francisco Omar López-Fuerte through April 2016 to estimate age and individual growth. Total lengths (TL) Email address for contact author: [email protected] ranged between 15.3 and 35.5 cm for males and between 19.0 and 44.5 cm 1 Departamento de Pesquerías y Biología Marina 2 Laboratorio de Sistemas Arrecifales for females. Results from analysis of Centro Interdisciplinario de Ciencias Marinas Departamento Académico de Ciencias the edge types of otoliths (opaque and Instituto Politécnico Nacional Marinas y Costeras translucent) indicate an annual period- Avenida Instituto Politécnico Nacional s/n Universidad Autónoma de Baja California Sur icity in the formation of annuli in sagit- Colonia Playa Palo de Santa Rita Carretera al Sur km 5.5 tae. Ages of stone scorpionfish ranged Apartado Postal 592 23080 La Paz, Baja California Sur, Mexico from 2 to 10 years for males and from 23096 La Paz, Baja California Sur, Mexico 3 to 15 years for females. Estimates for the parameters of the von Berta- lanffy growth function were 34.76 and 48.22 cm TL for asymptotic length, 0.202/year and 0.135/year for growth coefficient, and −1.28 and −0.80 years for theoretical age at length zero for The stone scorpionfish (Scorpaena mys- the catches of other species of high males and females, respectively. This tes) is commonly found throughout the commercial value, such as the Pacific study resulted in the first estimates of age and individual growth of stone Gulf of California in Mexico, with a dis- red snapper (Lutjanus peru) and yel- scorpionfish, information that is essen- tribution in the eastern Pacific Ocean lowtail jack (Seriola lalandi), caused tial for evaluation and management of that extends from southern California to an increase in price and capture vol- this important fishery resource. Chile, including offshore islands (Butler ume of the stone scorpionfish, driving et al., 2012). This demersal species occurs this species into the commercial sec- in shallow waters and seaweed-covered tor as a complementary, high-quality reefs as well as in open, sandy areas to product. depths of 85 m. It is considered an oppor- Given the little amount of data avail- tunistic predator and feeds mainly on able on the basic biological characteris- crustaceans and small fish (Butler et al., tics of this species and its recent 2012). Adults reach sizes up to 51 cm in commercial exploitation in the region total length (TL) (Robertson and Allen, of the Gulf of California, there is an 2015). urgent need to document its basic life The meat of stone scorpionfish is history (e.g., age, growth, mortality, considered to be of excellent quality and reproduction) and its population and has high commercial value; as dynamics and to create a management a result, this species has become an protocol for this fishery resource. Age important fishery resource (J akes-Cota and individual growth should be Manuscript submitted 14 May 2020. et al., 2017). Historically, however, included as key elements in every Manuscript accepted 15 October 2020. this species has not been sought after investigation focused on the rational Fish. Bull. 118:324–328 (2020). Online publication date: 29 October 2020. commercially because venom glands exploitation of fishing resources doi: 10.7755/FB.118.4.2 located along the spines of the fins (Beamish and Fournier, 1981). Prior to can cause painful injuries and severe this study, the age and individual The views and opinions expressed or respiratory disorders (Poss, 1995); it growth characteristics of stone scorpi- implied in this article are those of the has long been a secondary priority spe- onfish were not available; therefore, author (or authors) and do not necessarily reflect the position of the National cies in the artisanal fishery in the Gulf the aims of our study were 1) to esti- Marine Fisheries Service, NOAA. of California. Since 2012, decreases in mate age by using otoliths, 2) to Jakes-Cota et al.: Age and growth of Scorpaena mystes 325 National Marine estimate individual growth parameters, Fisheries Service Fishery Bulletin First U.S. Commissioner and 3) to test for significant differences established in 1881 of Fisheries and founder NOAA of Fishery Bulletin in growth trajectories between males and females. Materials and methods Stone scorpionfish were collected once a month (21–22 individuals per month) in the artisanal fishery from May 2015 through April 2016. The fish were taken by spearing while using semiau- tonomous diving equipment (hookah), at depths up to 30 m, at different fish- ing sites along 20 km of coastline south of the harbor of Santa Rosalia in Baja California Sur, Mexico. The standard length (SL) and TL were measured to the nearest millimeter, and the weight Figure 1 (W) was recorded to the nearest 0.1 g Photograph showing the annular pattern in the sagittae of a 4-year-old male for each individual. Sex was deter- stone scorpionfish (Scorpaena mystes) caught in May 2015 in the Gulf of mined by using macroscopic exam- California in Mexico. Black dots indicate annuli. The black arrow indicates the ination of the gonads, and the exact measurement of the otolith radius. The scale bar is equal to 1 mm. binomial test was used to test differ- ences in sex ratio. Pairs of sagittae were extracted, cleaned, and stored dry in plastic vials in the laboratory, and only the right otoliths software AxioVision, vers. 4.6 (Carl Zeiss AG). The ste- were used for the analyses described in the rest of this reoscope was attached to a digital camera (AxioCam section. MRc 5, Carl Zeiss AG). The relationship between TL and To describe the length–weight relationship, we used this OR was described by using a simple linear regression equation: analysis. Right otoliths were immersed in ethanol with the con- W = aTLb, (1) cave side down, and 2 independent readers counted the where a = the intercept of the regression line; and annuli once with a stereoscope, using reflected light b = the allometric coefficient, the slope of the regres- against a dark background without prior knowledge of sion line. fish length or weight. Under reflected light, the nucleus (the core of the otolith) and the opaque bands appeared To describe the relationship independently for males and as light rings and the translucent bands appeared as dark females with log-transformed length and weight data, we rings (e.g., La Mesa et al., 2005, 2010; Bilgin and Çelik, used this equation: 2009). The combination of an opaque band followed by log W = a + blog TL. (2) a translucent band was considered to be an annulus, as has been done for other scorpionfish species (e.g., Massutí The a and b parameters were estimated by using a sim- et al., 2000; La Mesa et al., 2005, 2010; Bilgin and Çelik, ple linear regression analysis. A Student’s t-test was 2009). Annuli were counted from the nucleus toward the performed to evaluate whether the b-value was signifi- tip of the rostrum (the anterior projection of the otolith) cantly different from 3, a value that indicates an isometric along the same line (Fig. 1). The precision between readers growth pattern (i.e., all body parts grow at approximately was evaluated by using the mean coefficient of variation the same rate, and a fish has an unchanging body form (CV) and average percent error (APE). Values of 5.5% for throughout development). An analysis of covariance was APE and of 7.6% for CV have been considered adequate in used to test differences in b-values between males and many aging studies (Campana, 2001). females. To validate the periodicity of the formation of opaque The otolith radius (OR) (Fig. 1) was measured under 1 and translucent bands and to assign a unit of time (e.g., a stereoscope (Stemi SV11 , Carl Zeiss AG, Oberkochen, years) to the counted annuli, edge type analysis was Germany) at 3.2× magnification by using the imaging used. For this analysis, the edge type of each otolith was recorded as either opaque or translucent, and, for each month, the percentages of opaque edges and of translu- 1 Mention of trade names or commercial companies is for identi- fication purposes only and does not imply endorsement by the cent edges in the total number of otoliths analyzed was National Marine Fisheries Service, NOAA. plotted. 326 Fishery Bulletin 118(4) The von Bertalanffy growth function was fitted to Otolith radius ranged between 2.5 and 5.6 mm. The lin- length-at-age data to estimate individual growth: ear regression model developed to predict the relationship between OR and TL was as follows: (3) TL = −3.53 + 3.91OR. (4) The linear relationship between both variables was signif- where L = the length (TL, in centimeters) at age t; t icant (coefficient of determination [r2]=0.79, P<0.05). L = the asymptotic length; ∞ The highest percentage of otoliths with opaque edges k = the growth coefficient; and was recorded in August (81%), followed by the percentage t = the theoretical age at length zero.