Fisheries observers as enforcement assets: Lessons from the North Pacific

Fisheries observers can both collect scientific data and report on compliance with fisheries regulations. Observers are used only for scientific purposes in most US fisheries. However, North Pacific groundfish fisheries observers are required to report violations of fisheries regulations that they witness. Based on evaluation of historical enforcement incidents and survey data, this paper considers the effects of mandatory reporting in the North Pacific. The goal of this analysis is to determine whether and how observer enforcement in the North Pacific differs from observer enforcement in other US fisheries and to determine what benefits observer enforcement might yield if adopted in other fisheries.     

Observer precision and bird conspicuousness during counts of birds at sea

Simultaneous transect counts of seabirds by pairs of experienced, ship-based observers were compared to estimate count precision, defined as the proportion of birds counted by both observers. Precision was low; at most 51 per cent for all birds combined, with values for different taxa ranging between 0 and 57 per cent. High abundance of birds and large body size (greater conspicuousness) tended to increase count precision, whereas ship-following behaviour decreased precision. Two main sources of imprecision were identified: failure to correctly categorize birds (in or out of the transect area, passing or following the ship) and failure to detect birds. Incorrect categorization could be avoided by adequate training. Biases caused by specific differences in detectability could be reduced by increasing vigilance and by making use of the best possible vantage. Calculation of values of observer precision permits an estimate of the reliability with which different species are detected.     

The visual estimation of shore-breaking wave heights

Although a number of programmes for the visual estimation of breaking wave height have been, or are being, operated in different parts of the world (USA-LEO, Australia-COPE), there has been little investigation of the reliability of such data to make precise evaluations of breaking wave height. Using a combination of field data for simultaneous visual estimations and measurements of breaking wave height, it can be shown that experienced observers are able to estimate mean height with only a 20% error. Also the moments of the breaking wave spectrum may be calculated, allowing quick and cheap measurements of extreme waves.LEO records from Florida and California indicate that almost 50% of the data are redundant as frequency of observation could be halved without loss. However, records appear to be filtered, inasmuch as extreme waves are underestimated.     

Estimation of hydrodynamic coefficients for an AUV using nonlinear observers

Hydrodynamic coefficients strongly affect the dynamic performance of an autonomous underwater vehicle. Although these coefficients are generally obtained experimentally such as through the planar-motion-mechanism (PMM) test, the measured values are not completely reliable because of experimental difficulties and errors involved. Another approach by which these coefficients can be obtained is the observer method, in which a model-based estimation algorithm predicts the coefficients. In this paper, the hydrodynamic coefficients are estimated using two nonlinear observers - a sliding mode observer and an extended Kalman filter. Their performances are evaluated by comparing the estimated coefficients obtained from the two observer methods with the values as determined from the PMM test. By using the estimated coefficients, a sliding mode controller is constructed for the diving and steering maneuver. It is demonstrated that the controller with the estimated values maintains the desired depth and path with sufficient accuracy.     

一类离散非线性系统降维观测器设计

讨论了一类离散非线性系统降维观测器的存在性。对给定的Lyapunov函数,在保证观测误差渐近稳定的条件下,给出了该离散非线性系统降维观测器的设计方法。用数值例子说明了该设计方法的有效性。     

天文经度测量中人仪差测定精度评估方法研究

在天文经度测量中,由观测员及其所用仪器引起的误差称为人仪差,在一、二等天文测量中必须加入此项改正。采用1992年至2012年间,21名观测员的144组人仪差成果,分别统计分析了人仪差分布情况和人仪差变化分布情况,使用多种数学模型进行了精度估计。人仪差和人仪差变化符合正态分布规律,数学期望接近于0。评定天文经度测量成果时,人仪差变化中误差取±0.02s较为合适。     

Patterns and trends in seabird bycatch in the pelagic longline fishery off South Africa

Both foreign and domestic pelagic longline fishing vessels operate in South Africa’s Exclusive Economic Zone and adjacent international waters where they kill hundreds of seabirds each year as bycatch. To update assessments of the impact of the pelagic longline fishery on seabirds off South Africa, information on necropsied seabirds and national fisheries observer bycatch records were summarised for 2006–2013. Foreign-flagged (Asian) vessels had 100% observer coverage throughout the study period, whereas only 6% of the fishing effort by South African-flagged vessels was observed (with no coverage in 2011–2013). Vessels with observers caught seabirds at a rate of 0.132 birds per 1 000 hooks, resulting in an estimated mortality of 2 851 individuals (356 per year) comprising 14 species. Extrapolation of the observed fishing sets to the unobserved fishing sets by the South African domestic longline fleet suggested that approximately 750 additional birds were likely killed during the study period, therefore a combined 450 birds were killed per year. White-chinned petrel Procellaria aequinoctialis was the most frequently killed species (66%), followed by ‘shy-type’ albatrosses Thalassarche cauta/steadi (21%), black-browed albatross T. melanophris (7%), Indian yellow-nosed albatross T. carteri (3%), and Cape gannet Morus capensis (2%). The seabird bycatch rates were lower than in 1998–2005. Nationality of the vessel, time of line-setting, moon phase, year, season, fishing area, and seabird bycatch mitigation measures all influenced seabird mortality. Concurrent with 100% observer coverage, significant reductions in the seabird bycatch rate occurred in the Asian fleet in the latter years of the study, and these rates now approximate the national target (0.05 birds per 1 000 hooks). However, seabird bycatch rates remained high in the South African fleet, where no observers were deployed during 2011–2013, highlighting the need for independent observer programmes in fisheries—a matter of global interest. Suggestions are made as to how seabird bycatch by pelagic longline fisheries off South Africa may be further reduced.     

Nonlinear control of an active heave compensation system

Heave motion of a vessel or a rig has an adverse impact on the response of a drill-string or a riser. To compensate for heave motion, passive and active devices are usually used. Active heave compensators, in which a control system is an essential part, allow conducting operations under more extreme weather conditions than passive ones. This paper presents a constructive method to design a nonlinear controller for an active heave compensation system using an electro-hydraulic system driven by a double rod actuator. The control system reduces the effect of the heave motion of the vessel on the response of the riser by regulating the distance from the upper end of the riser to the seabed. The control development is based on Lyapunov's direct method and disturbance observers. The paper also includes a method to select the control and disturbance observer gains such that actuator saturations are avoided. Stability of the closed loop system is carefully examined. Simulation results illustrate the effectiveness of the proposed control system.     

Emerging fisheries,emerging fishery interactions with sea turtles: A case study of the large-mesh gillnet fishery for flounder in Pamlico Sound,North Carolina,USA

Emerging fisheries and changes in fishery practices are not always readily apparent, nor are their impacts on non-target species such as seabirds, sea turtles, and marine mammals. Data from several different sources led managers to discover high rates of sea turtle bycatch in an inshore large-mesh gillnet fishery in North Carolina, USA, particularly the emerging deep-water gillnet fishery. This paper reviews the history of how increased numbers of observed stranded sea turtles in 1999 led to the discovery that turtles were becoming entangled in the large-mesh gillnet fishery in Pamlico Sound, North Carolina. It also demonstrates how a variety of data sets from fisheries observers, aerial surveys, and fisheries statistics programs contributed to shaping management of the large-mesh gillnet fishery in Pamlico Sound to decrease turtle bycatch and now point towards the need of additional assessment of gillnet bycatch in other parts of North Carolina. Finally, potential approaches are discussed for a more timely detection of future fishery conflicts and development of a plan to reduce otherwise inevitable bycatch and disruptions to fishing effort.     

UNCLOS and the marine scientist

The deliberations at UNCLOS have been watched with great interest by individual marine scientists and by those who have attended as observers on behalf of scientific groups. Most of all these scientists have been apprehensive that their ability (freedom) to carry out research would be significantly limited by many of the provisions of the ICNT. In fact, one author goes as far as to state that progress has been made, largely at the expense of the marine research scientist¹.     

CCAMLR process of risk assessment to minimise the effects of longline fishing mortality on seabirds

We describe the process used in the fisheries management system of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) to minimise seabird bycatch, and the risk-assessment methodology developed to assist this. We examine the progress of several Regional Fishery Management Organisations in taking steps to address seabird bycatch. CCAMLR has the most advanced system of management among the RFMOS covered in this review, and has made the most demonstrable progress in reducing seabird bycatch levels in its longline fisheries. A combination of proven mitigation measures, extensive monitoring by independent observers, annual expert review of seabird bycatch rates and evolving fishery and mitigation practices have been instrumental in reducing seabird bycatch in CCAMLR fisheries.     

Migration dynamics of Pacific herring (Clupea pallasii) and response to spring environmental variability in the southeastern Bering Sea

In the southeastern Bering Sea, Pacific herring (Clupea pallasii) migrate from the Pribilof Islands region where they overwinter, to the Alaska coast where they spawn in spring. The migration sustains a nearshore commercial fishery that targets roe-bearing females just prior to spawning. Herring also are taken as bycatch in groundfish trawl fisheries, where time and area closures in these fisheries are triggered by herring bycatch caps. Using herring bycatch data collected since the 1970s by National Marine Fisheries Service (NMFS) observers aboard groundfish fishing vessels, a retrospective analysis was conducted to describe the seasonal migration pattern of Pacific herring in the southeastern Bering Sea and to study its spatial and temporal variability. Observed changes in herring catch per unit of effort were compared with variability in climate and oceanographic conditions. The seasonal migration is complex, but annual shifts in migration routes and a possible northward shift of the overwintering grounds was identified. Pre-spawning herring aggregated in different areas depending on whether spawning occurred early or late in spring. The thermal structure of the ocean around the ice edge appears to influence herring migration timing and route as well as spawning date. Thus, on the basis of recent changes in sea-ice extent and duration, we suggest that the herring bycatch savings area that was developed from data collected in the 1980s should be revised to reflect prevailing conditions.     

Legal and institutional tools to mitigate marine turtle bycatch: Argentina as a case study

This paper explores conservation policy pertinent to three species of marine turtles affected by fisheries, while crossing jurisdictions in their seasonal migrations through the SW Atlantic, particularly the Argentine waters. This case study reviews local legal and institutional frameworks for Argentina and concludes that tools are in place to monitor and mitigate the negative impact of bycatch on the populations. Argentina is signatory of the most relevant international treaties aimed at protecting transboundary species (e.g. Inter-American Convention for the Protection and Conservation of Sea Turtles, Convention on the Conservation of Migratory Species of Wild Animals). Legislation also exists at the federal and provincial levels. Yet, accidental captures continue to occur due to weaknesses in enforcement and the low priority that conservation has in fisheries management decisions. Some urgent practical actions supported by policy are suggested: (a) placement of on-board observers in coastal fishing fleets, (b) application of existing mitigation measures to reduce bycatch, (c) design of a national plan of action for marine turtles in Argentina, and (d) development of a regional plan between Argentina, Brazil and Uruguay. Stakeholder involvement, especially the fishing sector but also the civil society, would be important to energize practical and effective conservation decisions. The example of Argentina is typical for the region and may apply to other countries as well. The conservation community requires investing more in the application of policy, concomitant with perfecting legal tools.     

Seabird bycatch by tuna longline fisheries off southern Africa, 1998–2000

The incidental mortality of seabirds in tuna longline fisheries is estimated for the continental South African Exclusive Economic Zone (EEZ). Fishery observers accompanied 13 fishing trips and observed 108 sets (143 260 hooks) during the period 1998–2000. Despite most lines being set at night, seabird bycatch rates were high, with a mean of 1.6 birds killed per 1 000 hooks. Japanese vessels (1% effort observed) had a higher bycatch rate (2.6 birds per 1 000 hooks, range per trip 0.1–5.4) than South African vessels (0.8, range 0.0–4.3; 17% effort observed), possibly as a result of gear differences. Bird bycatch differed regionally in relation to the numbers of birds attending vessels. In international waters off the Northern Cape and southern Namibia, where there are few birds, only one bird was caught on 93 600 hooks (0.01 birds per 1 000 hooks). Shy Thalassarche cauta, black-browed T. melanophris and yellow-nosed T. chlororhynchos albatrosses, and white-chinned petrels Procellaria aequinoctialis were killed most frequently. Based on 1998–1999 fishing effort, simple extrapolation suggests that 19 000–30 000 seabirds are killed annually in South Africa's EEZ, of which 70% are albatrosses. Confidence in these estimates is low, given the small proportion of effort observed, but it is clear that urgent steps are needed to reduce seabird bycatch within South African waters.     

Reduced seabird night strikes and mortality in the Tristan rock lobster fishery

The main impact of the fishery for Tristan rock lobster Jasus tristani on seabirds at the Tristan archipelago and Gough Island is through night strikes, when petrels collide with a ship after being disorientated by its lights. Tristan fishery observers have kept records of night strikes on the MV Edinburgh since the 2010/2011 fishing season. Over the last three years, 723 seabirds from nine species were recorded coming aboard the fishing vessel, with at least 39 (5.4%) birds dying as a result. Birds killed were broad-billed prions Pachyptila vittata (41%), common diving petrels Pelecanoides urinatrix (23%), and storm petrels (Pelagodroma marina and Fregetta grallaria/tropica 36%). All these species are listed as Least Concern globally, and the numbers killed per year are <0.1% of the island populations. The captain and crew of the Edinburgh are aware of the problem posed by deck lights at night, and attempt to keep external lighting to a minimum. As a result, the numbers of birds coming aboard vessels in this fishery have decreased from an average of 130 birds per night in 1989 to less than two birds per night in 2010–2013. Currently, most incidents occur during exceptional events when circumstances require deck lights to be lit at night. Consideration should be given to banning fishing operations at night, at least on misty nights.     

Remote electronic monitoring and the landing obligation – some insights into fishers’ and fishery inspectors’ opinions

The European fisheries management is currently undergoing a fundamental change in the handling of catches of commercial fisheries with the implementation of the 2013 Common Fisheries Policy. One of the main objectives of the policy is to end the practice of discarding in the EU by 2019. However, for such changes to be successful, it is vital to ensure stakeholders acceptance, and it is prudent to consider possible means to verify compliance with the new regulation. Remote Electronic Monitoring (REM) with Closed-Circuit Television (CCTV) has been tested in a variety of fisheries worldwide for different purposes and is currently considered as one possible tool to ensure compliance with a European ban on discards.This study focuses on Danish fishery inspectors and on fishers with REM experience, whose opinions are less well known. Their views on the landing obligation and on the use of REM were investigated using interviews and questionnaires, and contrasted to some fishers without REM experience. 80% of fishery inspectors and 58% of REM-experienced fishers expressed positive views on REM. 9 out of 10 interviewed fishers without REM experience were against REM. Participation in a REM trial has not led to antipathy towards REM. Fishery inspectors saw on-board observers, at-sea control and REM as the three best solutions to control the landing obligation but shared the general belief that the landing obligation cannot be enforced properly and will be difficult for fishers to comply with. The strengths and weaknesses of REM in this context are discussed.     

Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines

Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill (Euphausia superba).     

The application of visual census on Mediterranean rocky habitats

In this study we examined the effect of: observer presence; observer speed; and the impact that multiple surveys had on the number of counted fish in a visual census survey in a typical Mediterranean rocky habitat. SCUBA observer presence had no influence on the number of fish per survey. An improvement in the methodology to estimate the number of fish was demonstrated by using two different speeds: slow speed for benthic species and higher speed for epibenthic ones. No differences in the number of fish per survey were found among successive surveys along the same transects, even with the shortest time interval used: 5 min. We also examined the ability of observers to estimate fish length during visual census by using wooden fish models. Significant differences in size estimations were found using two different estimation methods (i.e. size-classes estimates and continuous measures). Estimating fish length to a size class was more accurate in estimating size, while transformed size to calculate biomass from length estimates was more accurate using continuous measures.     

Marine renewables and coastal communities—Experiences from the offshore oil industry in the 1970s and their relevance to marine renewables in the 2010s

Ambition to create jobs and economic growth from the vast open spaces of the oceans and seas is made real by new and developing technologies. In the 2010s, renewable energy generated from wind, wave and tide is laying claim to large areas of marine space and driving the search to find new ways to manage ocean and coastal development. Many more activities are expected and precedents are currently being set for the future of marine governance. Several observers have drawn parallels with the development of offshore oil and gas in the 1970s, which also represented a step change in use of the seas and coasts. The change was particularly felt in the Orkney and Shetland archipelagos, at the centre of the North Sea oilfields. Special powers were granted to the county councils here to control development and share in its benefits. This paper compares the oil and renewables industries, separated in time by nearly 40 years, and their influence on adjacent communities. The similarities and differences are identified to test the hypothesis that the 1970s oil model of local participation could be repeated for the development of marine renewables in the 2010s. The conclusion is that the model could well be applied but that the political and policy drivers of today make it unlikely, at least for the time being. Most notably, the change in the role of the public and private sectors and the use of market instruments to achieve national objectives tend to favour a climate of central control.