To estimate the health of the California sheephead Semicossyphus pulcher fishery, a 2004 stock assessment used available biological data that were collected decades prior to an increase in fishing pressure. However, a recent study has found that sex ratios, growth rates, survivorship, and average sizes of females and males have changed in response to size‐selective fishing in some California sheephead populations. To better understand the potential changes in protogynous California sheephead, this study sought to determine (1) whether external morphology was still an accurate method of predicting sex in sexually dimorphic California sheephead at Santa Catalina Island, California, and (2) whether nonlethal blood sampling and plasma hormone analysis could be used to predict sex for future stock assessments. Sex was determined using gonadal histology and compared with several specific external morphological characters. Estradiol and 11‐ketotestosterone plasma concentrations were also compared across sexed individuals. The rate of error when using external morphology alone to predict sex was 58%. In contrast, sex steroid concentrations varied significantly across sexes; estradiol concentrations were significantly greater in females than in transitioning and male individuals during the breeding season, and 11‐ketotestosterone concentrations were significantly lower among females. Gonadal histology showed that 21% of the fish caught during the breeding season were classified as transitional, in stark contrast to historical data. The inability to accurately predict sex using external morphology alone suggests that commonly used methods of surveying California sheephead populations (e.g., diver surveys) may be inaccurate. Nonlethal blood sampling and subsequent plasma hormone analysis may offer an alternative method for assessing sex in California sheephead. Because California sheephead are not reproductively functional during transition and because we found such a large proportion in transition during the breeding season at Santa Catalina Island, we believe there is a need for continued assessment of the reproductive potential in this population of California sheephead.

中文翻译：

---

利用形态学和内分泌学预测加利福尼亚羊头的性行为：加利福尼亚圣卡塔琳娜岛的性变化时机改变的证据。

评估加利福尼亚羊头半cos鱼的健康状况渔业，2004年种群评估使用了在捕捞压力增加之前几十年收集的可用生物学数据。但是，最近的一项研究发现，在加利福尼亚的一些羊头种群中，性别比例，生长速度，生存率以及雌雄平均大小已经发生变化，这是由于选择了大小捕捞而引起的。为了更好地了解原产于加利福尼亚的羊头的潜在变化，本研究试图确定（1）外部形态是否仍然是预测加利福尼亚州圣卡塔琳娜岛有性双态加利福尼亚羊头性别的准确方法，以及（2）是否进行非致命性血液采样血浆激素分析可用于预测性别，以便将来进行库存评估。使用性腺组织学确定性别，并与几个特定的​​外部形态特征进行比较。还比较了性别个体中的雌二醇和11-酮睾酮的血浆浓度。仅使用外部形态学预测性别时的错误率为58％。相反，性别中的类固醇浓度差异很大。在繁殖季节，雌性雌二醇的浓度显着高于过渡期和雄性，雌性中的11-酮睾酮浓度显着降低。性腺组织学研究表明，在繁殖季节捕获的鱼中有21％被归类为过渡鱼，与历史数据形成鲜明对比。仅靠外部形态无法准确预测性别，这表明调查加利福尼亚羊头种群的常用方法（例如，潜水员调查）可能不准确。非致命性血液采样和随后的血浆激素分析可能为评估加州羊头的性别提供另一种方法。由于加利福尼亚羊头在过渡期间没有生殖功能，并且因为我们在圣卡塔利娜岛的繁殖季节发现了如此大的过渡期，因此我们认为有必要继续评估加利福尼亚羊头种群的繁殖潜力。