Use of laparoscopy to determine sex and reproductive status of shortnose sturgeon (Acipenser brevirostrum) and Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus)

Abstract

Sex and reproductive maturity of Atlantic and shortnose sturgeon were determined by visual examination of the gonads using laparoscopy, and were validated by histological examination of gonadal biopsies. Surgical anesthesia was induced in all fish with 250 mg L )1 tricaine methanesulfonate (MS-222) and maintained throughout procedures with 85 mg L )1 MS-222 on a mobile surgical cart. A pair of Ternamian EndoTip cannulae installed through the ventral body wall in each fish, allowed access for a 5-mm rigid laparoscope and biopsy forceps. Video endocamera use with the laparoscope, following air insufflation of the coelom, provided detailed, high quality imagery to aspirate the swim bladder, examine the gonad and collect biopsies without inducing iatrogenic trauma. Germinal tissue of all immature males, 25% of immature female shortnose sturgeon and 45% of immature female Atlantic sturgeon were concealed by fat preventing sex determination by visual assessment. Morphological features of gonads were used to determine sex in all remaining fish and were 100% in concordance with histological findings. Relative amount of gonadal fat; gonad size and color; presence of testicular lobes or ovarian lamellae; and color, size and density of oocytes were useful in determining reproductive stage. Gonad morphology of each reproductive stage was similar in Atlantic and shortnose sturgeon. All captive Atlantic sturgeon survived laparoscopy, gained weight at the same rate as unexamined fish and scars from incisions were no longer evident 9-12 months after surgery. Laparoscopic procedures presented here offer a safe and highly reliable way to determine sex and reproductive status for Atlantic and shortnose sturgeon.

Evaluation of tricaine methanesulfonate (MS-222) as a surgical anesthetic for Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus

“…Dose‐response trials were also conducted to evaluate the ability of MS‐222 to maintain surgical anesthesia for a period of 45 min. Three identical recirculating anesthesia machines (Matsche et al., 2011) were filled with 60 L each of the following anesthetic maintenance solutions: (i) 70 mg L −1 MS‐222 and 140 mg L −1 NaHCO 3 , (ii) 85 mg L −1 MS‐222 and 170 mg L −1 NaHCO 3 , or (iii) 100 mg L −1 MS‐222 and 200 mg L −1 NaHCO 3 . Outflow rate of anesthetic solution on each machine was adjusted to 2 L min −1 and tanks of anesthetic solutions were aerated.…”

“…Captive propagation of sturgeon may be a viable management option for stock enhancement (Smith, 1990; Waldman and Wirgin, 1998) and for production of meat and caviar to reduce fishing pressure on wild populations. Assessments of wild and captive populations depend on the ability to collect detailed information on the physiological and reproductive state of fish, and for sturgeon, this often requires post‐mortem or surgical examination of internal anatomy or collection of tissue biopsies for microscopic examination (Bruch et al., 2001; Divers et al., 2009; Matsche et al., 2011). Non‐lethal handling and sampling techniques are particularly important for imperiled species and to monitor potential broodstock for captive propagation efforts.…”

“…In sturgeon, coeliotomy (access to body cavity through abdominal incisions) is commonly used to implant telemetry devices (Collins et al., 2000; Fox et al., 2000; DeLonay et al., 2007; Erickson and Webb, 2007) and to examine and biopsy gonads for gender and maturity determinations (Conte et al., 1988; Mohler, 2004; Paragamian et al., 2005; Webb and Erickson, 2007). Recently, endoscopy has been favored as a less invasive alternative to coeliotomy to obtain reproductive information from wild and captive sturgeon (Wildhaber et al., 2005; Hurvitz et al., 2007; Divers et al., 2009; Matsche et al., 2011). Anesthesia is an important component of invasive surgical procedures as fish that are not properly immobilized may be injured, and anesthetic drugs may lessen physiological changes associated with handling and surgery in some species and provide analgesia (Ross and Ross, 2008).…”

“…Lower concentrations of MS‐222 were recirculated over the gills to maintain anesthesia (and life support): in white sturgeon [75 mg L −1 , Conte et al. (1988)], shortnose sturgeon and Atlantic sturgeon [85 mg L −1 ; Matsche et al. (2011)], gulf sturgeon [87.5 mg L −1 ; Hernandez‐Divers et al.…”

Abdominal puncture as a new method to determine sex in tuviras ( Gymnotus sp.)

“…According to Filho et al (), the accuracy degree using this technique reached 96.3% for males and 93.9% for females of Lophiosilurus alexandri . Compared to coeliotomy, coelioscopy or endoscopy is a less‐invasive technique (Matsche, Bakal, & Rosemary, ). However, the application of this procedure requires equipment that costs approximately $4,000 USD.…”