Enhancing single-species stock assessments with diverse ecosystem perspectives: a case study for Gulf of Mexico Red Grouper (Epinephelus morio) and red tides

Impacts of Karenia brevis red tide blooms have been an increasing cause of concern for fisheries management in the Gulf of Mexico (Gulf). The 2019 Gulf red grouper stock assessment was confronted with the challenges of quantifying and parameterizing red tides during both historical and projection time-periods. Red tide mortality was estimated for each age-class in the model solely in 2005 and 2014 during severe events. Given the considerable uncertainty surrounding the 2018 red tide and its substantial implications on the status of the population, several projection scenarios were evaluated. Under the assumption of no 2018 red tide mortality, near-term catches were projected to nearly double, a predicted outcome that appeared to be in contrast to recent record low catches and fishing industry perceptions of significant stock depletion. In the event that the 2018 red tide caused mortality, but was not accounted for in projections, the recommended catch levels would lead to high probabilities of overfishing and potentially stock collapse. Collectively, these results highlight how consideration of uncertainty in projections can help avoid unintended consequences.

Decoupling and Decomposition Analysis of Land Natural Capital Utilization and Economic Growth: A Case Study in Ningxia Hui Autonomous Region, China

In order to reduce the depletion of land natural capital and develop economy simultaneously, it is necessary to study how to achieve the strong decoupling relationship between them. However, so far such studies have been relatively limited. Thus, taking the case of Ningxia Hui Autonomous Region, China, this paper firstly analyzes the state of land natural capital utilization in 1999–2017 by using improved ecological footprint. Then, decoupling state is quantified by Tapio decoupling model. Last, major driving factors on the decoupling relationship are explored with combination of LMDI decomposition and Kaya identity equation. Results showed that: (1) Both natural capital flows and stock depletion of cultivated land decrease obviously during the transition to corn-based intensive ecological agriculture. Grassland and water are the most unsustainable development sectors among all land types with their stock depletion intensified. Forest land and construction land could basically meet the consumer demand, but the flow occupancy of construction land is the fastest-growing segment. (2) Decoupling relationship is in an alternating state between weak decoupling and strong decoupling in 1999–2017. Wherein, the cultivated land and forest land showed a preferred decoupling state, followed by grassland, while the water and construction land showed the unfavorable expansive negative decoupling and weak decoupling. (3) Decomposition results show that intensity effect is the major factor that promotes the decoupling while economic effect inhibits the decoupling, but this negative impact is weakening in the process of industrial transformation. The other three factors affect less on the decoupling. This study has a certain reference value to construct an ecological civilization in eco-fragile regions and formulate relevant policies on the increase of land natural capital efficiency.

Stock depletion of yellowfin tuna Thunnus albacares (Bonnaterre 1788) in the Northeastern Indian Ocean

The stock of yellowfin tuna (Thunnus albacares) has been in a declining trend in the last five years. Although the noticeable decline mainly occurred in the western part of the Indian Ocean, uncertainty lingers on how this phenomenon will affect the opposite leg. The study aimed to investigate the dynamics of stock through monitoring several indicators by utilizing logbooks, scientific port sampling, and observer data available. The result showed that both relative abundance and estimated catch trend are declining in recent years, a sign that the negative global inclination also influences Indonesian tuna longline fisheries. Further studies are needed to understand whether this phenomenon also impacts other gears. Hence, mitigation on conserving the resource by reducing the catch and strengthening the data collection should be the priority to maintain the livelihood and welfare of many coastal communities.

Komposisi dan distribusi ukuran hasil tangkapan sampingan bubu ekor kuning di Perairan Kepulauan Seribu

Bycatch is non-target species which mostly caught at fishing operation. High quantity of bycatch mortality was predicted as one factor of fish stock depletion. Additionally, the high demand to improve fisheries production will be able to lead over fishing. This situation will affect improvement of bycatch and discarded species which will endanger the fish stock. The objective of this research was to identify bycatch composition, ratio between target species and bycatch and size distribution of dominant bycatch at yellow tail fishing operation in Seribu Islands. The research was carried out at Seribu Islands on July-August 2020. The fishing activity used pot with size length x width x height : 100 x 75 x 32.5 cm. Result of research indicated that yellow tail pot bycatch was dominated by brownstripe snapper (Lutjanus vitta) with catch amount of 330 fishes ( 15.9% of total catch) and weight of 50,861 kg (11.5% of total catch weight) followed by squirrelfishes (Sargocentron rubrum) with catch amount of 324 fishes (15.6 % of total catch) and weight of 51,181 kg (11.6%). Another dominant bycatch was striped spinecheek (Scolopsis margaritiferus) with catch amount of 289 fishes (13.9% of total catch) and weight of 40,042 kg (9.1% of total weight). Ratio of target of catch : bycatch in weight was 42.6% : 57.4%. It means, to catch 1 kg of yellow tail there will be caught 1.7 kg bycatch. Total length size of brownstripe snapper at range of 12-27 cm, squirrelfishes at range of 9-27 cm and striped spinecheek at range of 11-29 cm.Keywords:BycatchPotDiscard speciesYellow tailCatch compositionABSTRAKHasil tangkapan sampingan merupakan spesies hasil tangkapan non target yang relatif tinggi tertangkap pada operasi penangkapan. Tingginya jumlah kematian hasil tangkapan sampingan diduga menjadi salah satu penyebab menurunnya stok sumberdaya ikan di seluruh penjuru dunia. Adanya permintaan yang tinggi untuk meningkatkan produksi perikanan dapat memicu peningkatan upaya penangkapan secara berlebihan. Kondisi ini mengakibatkan hasil tangkapan sampingan akan meningkat dengan meningkatnya upaya penangkapan sehingga membahayakan stok dan populasi sumberdaya ikan. Penelitian ini bertujuan untuk mengidentifikasi komposisi hasil tangkapan sampingan, rasio antara hasil tangkapan utama dengan hasil tangkapan sampingan dan ukuran hasil tangkapan sampingan dominan yang tertangkap pada operasi penangkapan ikan ekor kuning di Perairan Kepulauan Seribu. Penelitian dilakukan di Perairan Kepulauan Seribu pada bulan Juli-Agustus 2020 dengan menggunakan bubu ekor kuning (ukuran p x l x t : 100 x 75 x 32,5 cm). Hasil penelitian menunjukan bahwa hasil tangkapan sampingan bubu ekor kuning didominasi oleh ikan kakap (Lutjanus vitta) dengan total jumlah hasil tangkapan mencapai 330 ekor ( 15,9%) dengan total bobot mencapai 50.861 kg (11,5%) disusul oleh ikan swanggi (Sargocentron rubrum) mencapai 324 ekor (15,6 %) dengan total bobot hasil tangkapan sebesar 51.181 kg (11,6%) dan ikan serak (Scolopsis margaritiferus) dengan jumlah hasil tangkapan mencapai 289 ekor (13,9%) dan bobot sebesar 40.042 kg (9,1%) dari total bobot hasil tangkapan bubu ekor kuning. Proporsi bobot hasil tangkapan utama dibanding dengan hasil tangkapan sampingan adalah 42,6% : 57,4%. Hal ini berarti untuk menangkap 1 kg ekor kuning maka akan tertangkap 1,354 kg hasil tangkapan sampingan. Ukuran hasil tangkapan sampingan dominan yang tertangkap pada bubu ekor kuning meliputi ikan kakap yang tertangkap pada selang ukuran panjang total 12-27 cm, ikan swanggi dengan selang ukuran panjang total berkisar 9-27 cm dan ikan serak dengan selang ukuran panjang total berkisar antara 11-29 cm.Kata kunci:Hasil tangkapan sampinganBubuDiscard spesiesIkan ekor kuningKomposisi hasil tangkapan

Overview of catch history, historic abundance and distribution of right whales in the western North Atlantic and in Cintra Bay, West Africa

The catch history of the North Atlantic right whales (Eubalaena glacialis) in the western North Atlantic has been studied in a series ofprojects. Data from European archives on early Basque whaling, centred in the Strait of Belle Isle, showed that there were at least a fewthousand right whales in the northern part of the range in the sixteenth century. Data from shore whaling in the eastern United Statessupplemented by British customs data indicated that there were still more than a thousand right whales in the southern part of the range(i.e. south from Nova Scotia) in the late seventeenth century. Right whales were depleted throughout the western North Atlantic by themiddle of the eighteenth century, but small shore whaling enterprises persisted in some areas and pelagic whalers continued to kill rightwhales opportunistically. An increase in alongshore whaling occurred at Long Island (New York) beginning in the 1850s and in North andSouth Carolina, Georgia and northern Florida in the 1870s-1880s. By the start of the twentieth century only a few crews of shore whalersremained active in Long Island and North Carolina, and their whaling efforts were desultory. All evidence points to stock depletion as theprimary reason for the demise of organised whaling for right whales in eastern North America. Recent sightings indicate that some rightwhales travel from the Bay of Fundy and Scotian Shelf far to the north and east, at least occasionally reaching the historic Cape FarewellGround. Areas known to have been used regularly by right whales in the past (e.g. Gulf of St Lawrence, Delaware Bay) are now visitedseasonally by only a few individuals. Recent surveys of Cintra Bay, a historic right whale wintering ground in the eastern North Atlantic,provided no evidence of continued use by right whales.

Shelf-based scarcity as a cue of luxuriousness: an application of psychophysiology

Purpose The purpose of this paper is to examine the perception of luxuriousness as a novel underlying mechanism of the shelf-based scarcity effect by using both psychophysiological measures (Study 1) and self-reported measures (Study 2). Design/methodology/approach Two within-subject experimental designs were conducted to examine the effects of low, medium and high stock depletion levels (i.e. shelf-based scarcity) on consumer responses. In Study 1, facial expression analysis was used to examine consumers’ liking, and left frontal asymmetry brainwaves were used to examine consumers’ approach motivation as a proxy for purchase intention. Study 2 extended the findings with self-reported measures. Findings In Study 1, perceived product luxuriousness was found to underlie the shelf-based scarcity effect on facial expressions and left frontal asymmetry brainwaves after controlling for other previously proposed mediators (i.e. product popularity and quality). The shelf-based scarcity effect is only observed between low vs high stock levels, whereas moderate stock level depletion does not evoke the shelf-based scarcity effect. Study 2 used self-reported measures to replicate the effect of shelf-based scarcity on product luxuriousness. However, the findings demonstrated the limitation of self-reported measures to identify a significant spill-over effect of perceived luxuriousness to attitude. Research limitations/implications Extending previous literature that relied heavily on self-reported measures, the current research used psychophysiological methods to uncover perceived luxuriousness as a novel underlying mechanism for the shelf-based scarcity effect. Thus, the findings are not only the first to provide psychophysiological evidence of the shelf-based scarcity effect but also to validate perceived luxuriousness as an underlying mechanism of the shelf-based scarcity effect. Practical implications The current findings suggest that the shelf-based scarcity effect is only evoked by high (instead of moderate) levels of stock depletion. The study also shows that shelf-based scarcity does not necessarily signal product popularity, but instead it may serve as a cue of product luxuriousness. Adding to other manipulations of retail spaces that elicit luxury perception (e.g. artwork, sensory delight and themed store atmospherics), this implies that businesses are able to use shelf-based scarcity as a cue to enhance or complement the luxury image or the perception of the brand or product. Originality/value The current research is the first study to use psychophysiological techniques to examine perceived luxuriousness as an underlying mechanism of shelf-based scarcity. It also demonstrates that self-report measures are not sensitive to such an effect in comparison to psychophysiological techniques, explaining why perceived luxuriousness has not been previously found to be an underlying mechanism of shelf-based scarcity.

Economics of climate change: introducing the Basic Climate Economic (BCE) model

Environmental economics models are often too complex to be communicated in an illustrative manner. For this reason, this paper develops the Basic Climate Economic (BCE) model that features core elements of macroeconomic and climate economic modelling, while allowing for an illustrative examination of the development path. The BCE model incorporates fossil stock depletion, pollution stock accumulation, endogenous growth, and climate-induced capital depreciation. We first use graphical analysis to show the effects of climate change and climate policy on economic development. Intuition for the different model mechanisms, the functional forms, and the effects of different climate policies is provided. We then show the model equations in mathematical terms to derive closed-form solutions and to run model simulations relating to the graphical part. Finally, we compare our setup to other models of climate economics.

An optimized catch-only assessment method for data poor fisheries

Catch statistics are perhaps the most commonly collected data and are widely available for many fisheries. However, it is currently difficult to provide scientific advice for management purposes using only catch data. This article presents a catch-only method for stock assessment of data-poor fisheries. It uses time series of catches and two priors, one for the intrinsic population growth rate derived from life history parameters, and another for stock depletion based on catch trends. The method applies an optimization algorithm to search the potential parameter space. All computations are model or equation based rather than using predefined rules. The utility of this method is demonstrated by applying it to 13 stocks in Australia that are assessed using Stock Synthesis—an assessment package that can make use of a variety of data sources. The estimated parameters, including carrying capacity, intrinsic population growth rate, maximum sustainable yield, and depletion from the catch-only method are broadly comparable with those from the full assessments. The circumstances in which the method may perform poorly, such as longer-term changes in productivity and episodic recruitment, are highlighted.