Linking vessel characteristics to accident severity in West African waters: a survival analysis

The grey triggerfish, Balistes capriscus, resource had declined for nearly two decades in West African waters; its distribution and growth remain to be reported after late 1980s. In order to fill this gap, specimens were collected during small pelagic fish stock assessment surveys in 2005 in coastal waters of Benin, Togo, Ghana and La Côte d'Ivoire (Western Gulf of Guinea) from 17 out of 165 swept-area hauls in depths range of 23–60 m. The modal size classes were 27.0–31.9 cm and 32.0–36.9 cm. The age classes were determined by interpreting growth rings on sections of first dorsal spines. Estimates of theoretical growth in length were obtained by fitting the observed length-at-age data to the standard form of von Bertalanffy growth equation. The estimated L∞ for B. capriscus was 45.1 ± 1.4 cm and the growth rate, K, was 0.21 yr-1. The phi prime (Ö') growth performance obtained was 2.63, which is comparable to that obtained in the 1980s on the same fish species in waters of Senegal, La Côte d'Ivoire and Ghana. The results suggest that the growth and distribution of grey triggerfish in the Western Gulf of Guinea had not changed, in spite of the apparent disappearance of the fish species in many areas of the West African coastal waters for nearly two decades.

Sustainable management of transboundary fish stocks hinges on accurate delineation of population structure. Genetic analysis offers a powerful tool to identify potential subpopulations within a seemingly homogenous stock, facilitating the development of effective, coordinated management strategies across international borders. Along the West African coast, the Atlantic chub mackerel (Scomber colias) is a commercially important and ecologically significant species, yet little is known about its genetic population structure and connectivity. Currently, the stock is managed as a single unit in West African waters despite new research suggesting morphological and adaptive differences. Here, eight microsatellite loci were genotyped on 1,169 individuals distributed across 33 sampling sites from Morocco (27.39°N) to Namibia (22.21°S). Bayesian clustering analysis depicts one homogeneous population across the studied area with null overall differentiation (F ST = 0.0001ns), which suggests panmixia and aligns with the migratory potential of this species. This finding has significant implications for the effective conservation and management of S. colias within a wide scope of its distribution across West African waters from the South of Morocco to the North-Centre of Namibia and underscores the need for increased regional cooperation in fisheries management and conservation.

IntroductionThe genus Pseudotolithus, commonly called croaker, is represented by the three main species found in West African waters.MethodsIn total, 934 individuals were sampled in 8 locations in Senegal, Ghana, and Nigeria. Several tests identified using sectioned otolith as the best method for determining the croakers' age. The marginal increment analysis validated the age data.ResultsThe relationship between total length and total weight was significant for all species. This relationship is significantly different according to the geographical area. There was significant sexual dimorphism in P. senegalensis and P. typus, and the reproduction period presented a significant effect on the body length-weight relationship of P. senegalensis. The von Bertalanffy growth model constrained by t0 = 0 was the best fit for the observed age data from the three species in the sampled countries. The asymptotic length TL∞ was estimated from 26.6 cm for P. elongatus on the Nigerian coast to 42.2 cm for P. senegalensis on the Senegalese coast. The growth rate K ranged from 0.58 for P. senegalensis to 1.12 for P. typus.DiscussionThe growth was significantly different among the three sampled countries for P. senegalensis. Conversely, there was no significant difference of growth between specimens of P. typus from Nigeria and Ghana. Finally, there was no significant sexual dimorphism in the growth of P. senegalensis in Senegalese waters. This new information on the biology of these three croaker species is essential for the future assessment and management of these commercial species in West African waters.

The International Regulations for the Prevention of Marine Pollution from ships (MARPOL 73/78) provided for the deployment of the oily-water separator (OWS) technology for the prevention of ship-based oily-water pollution in the marine ecosystem. Previous studies on the efficiency and effectiveness of the use of the OWS technology shows about 40 % failure rates and ineffective use; while also identifying a multiplicity of correlated factors constraining the effectiveness of the use of the technology onboard. To overcome the constraints posed by the identified factors to the effective use of the OWS technology requires a systems approach, which demands the determination of the dominant and significant factors constraining most, the effective use of the technology and prioritizing the elimination of the significant factors. The study used a survey design approach, employing primary data and the principal component factor analysis to determine the existence of about five principal factors, significantly constraining the effective use of the technology by ship operators in the West African Waters. The policy implications were discussed and recommendations for effective use of the technology proffered.

Fisheries have been recognised as a significant global threat to seabird populations through overfishing and bycatch. Yet, seabird–fishing interactions remain understudied in West African waters despite rich seabird biodiversity and intensive fishing activity occurring in the region. Using high‐resolution tracking data of seabirds and fishing and nonfishing vessels, we investigated the dynamics of interactions between nine seabird species and industrial fisheries in Northwest African waters. We also assessed the underlying factors (seabird breeding status; fishing vessel density, gear type, length and operational status; and environmental features) influencing seabird–fishing interactions. Furthermore, we pinpointed the relevant political stakeholders in such seabird–fishing interactions by identifying the type of fisheries, vessel nation flags and maritime zones involved. We found that, for each species, more than 70% of individuals encountered vessels within 30 km, with most of these encounters involving nonfishing vessels. However, Cape Verde shearwaters ( Calonectris edwardsii ), to a lesser extent, Cory's shearwaters ( Calonectris borealis ) and Audouin's gulls ( Ichthyaetus audouinii ) frequently approached fishing vessels within 1.5 km, exhibiting clear attending behaviour. Specifically, 66% of Cape Verde shearwaters, 27% of Cory's shearwaters and 50% of Audouin's gulls showed this close‐range association with fishing vessels. The probability of a seabird attending a fishing vessel was influenced by specific vessel features and environmental conditions (i.e. large vessels near the coast). Furthermore, we identified a range of flags within national waters, showing that nearly 20% of the interactions involved foreign‐flagged fishing vessels from Europe, Africa, Asia and Central America. Policy implications . This study provides guidance for seabird conservation by identifying high‐risk bycatch species and priority fishing fleets where mitigation should be targeted. It also demonstrates the potential of environmental variables to predict seabird–fishing interactions and underscores the political responsibilities essential for effective management in Northwest African waters.

The subfamily Asthenognathinae is currently composed of a single genus, Asthenognathus Stimpson, 1858, with three species, A. inaequipes Stimpson, 1858, A. hexagonus Rathbun, 1909 (both from the Indo-West Pacific), and A. atlanticus Monod, 1933 (European and West Tropical African waters). All Asthenognathus species are difficult to collect due to their small size and symbiotic lifestyle with fossorial organisms. The examination of specimens of A. atlanticus from European and West African waters deposited in scientific collections shows significant morphological and molecular differences with the Indo-West Pacific species, which makes the creation of a new subfamily (Schubartinae n. subf.) and two new genera necessary. The identity of A. atlanticus, the only species found along the East Atlantic and Mediterranean waters, is clarified, and a new genus, Dudekemus n. gen., is established for this species, Dudekemus atlanticus (Monod, 1933) n. gen., n. comb. This study also describes another new genus, Schubartus n. gen., based on morphological differences and genetic data. These two new genera can be distinguished from Asthenognathus by the carapace proportions and differences in the structures of the male pleonal somites, pereiopods and endostome. In addition, two new species distributed in Guinea-Bissau and Mauritania, Schubartus mauritanicus n. gen., sp. nov., and S. ngankeeae n. gen., n. sp., are described. A key for species of the subfamilies Asthenognathinae and Schubartinae n.subf. is provided.

The collection of the barnacle Chirona (Striatobalanus) amaryllis (Darwin 1954) (Crustacea, Cirripedia) from the hull of a ship that had been operating for five months in the Gulf of Guinea and off Sierra Leone triggered a closer investigation of the cirriped fauna of the West African coast. Both C. amaryllis and Megabalanus coccopoma can now be added to the list of successful invasions in tropical West African waters. This discovery, as well as the circumstances of the findings, necessitates an update of the invertebrate faunal inventory of tropical West African marine waters.

Most sophisticated stock assessment models often need a large amount of data to assess fish stocks, yet this data is often lacking for most fisheries worldwide, resulting in the increasing demand for data-limited stock assessment methods. To estimate fish stock status, one class of these data-limited methods uses simply catch time series data and, in other instances, life history information or fishery characteristics. These catch-only methods (COMs) built differently are known to make assumptions about changes in fishing effort and may perform differently under various fishing scenarios. As a case study, this paper used European anchovy (Engraulis encrasicolus) caught in the northwest African waters, though very economically and ecologically important, but still unassessed. Our study investigated the performance of five COMs under different fishing scenarios using as a reference the life-history information of the European anchovy captured in this region of the Atlantic. Hence, the present study developed a simulation approach to evaluate the performance of the five COMs in inferring the stock biomass status (B/BMSY) with consideration of different fishing scenarios under prior information true to anchovy. All five COMs mostly underestimated B/BMSY throughout the simulation period, especially under constant fishing mortality, and in the last five years of the simulation during all fishing scenarios. Overall, these COMs were generally poor classifiers of stock status, however, the state-space COM (SSCOM) generally performed better than the other COMs as it showed possibilities of recovering an overfished stock. When these methods were explored using actual anchovy catch data collected in the northwest African waters, SSCOM yielded results that were deferred from the other COMs. This study being the first to assess this species’ stock in this area using a suite of COMs, presents more insights into the species stock status, and what needs to be considered before scientifically putting in place management measures of the stock in the area.

For the Benguela-Belize Compliant Piled Tower (CPT), the interim construction phases during the installation played an important role in the structural design. Because of susceptibility to fatigue of the unfinished tower, in combination with weather sensitive installation phases, it was crucial to find the most accurate way to predict weather downtime during construction and hence assess the interim construction fatigue exposure. Workability assessments using detailed hindcast data, accurate wave forecasting and offshore decision support assisted to control the fatigue design aspect both in the engineering and installation phase. Due to various delays, the installation of the CPT was pushed beyond the favorable installation period, resulting in potential high interim construction fatigue exposure. By using ballast tanks, temporarily replacing the topsides weight during construction, the allowable interim period before the topsides were set could be increased. During the offshore installation, a combination of accurate weather forecasts and the ability to predict the SSCV's motion behavior during critical installation activities has proven to be successful, as the necessary installation windows were identified in time with the best possible accuracy and no critical installation weather windows were missed. Introduction On April 1st 2003, Cabinda Gulf Oil Company Ltd. awarded the EPCI Contract for the Benguela-Belize Compliant tower to Daewoo Shipbuilding and Marine Engineering Company Ltd (DSME) and Heerema Marine Contractors Nederland B.V (HMC) as the EPCI installation Subcontractor. The detailed design of the Compliant Piled Tower and the Topsides was subcontracted to Mustang Engineering Inc (MILP) and Kvaerner Brown and Root (KBR) respectively. The CABGOC Benguela-Belize Compliant Tower was the first Compliant Tower installed in West Africa and outside the Gulf of Mexico (GoM). MILP pioneered the CPT concept and designed all the existing towers in the GoM (Lena, Petronius and Baldpate). With the benefit of this experience, MILP performed an early FEED study for CABGOC in which not all installation related issues associated with the swell-dominated West African waters were addressed. HMC previously installed the Baldpate CPT in the GoM, and has performed various heavy lifts in West African waters but all in the period mid November to early March. Never before had a 10,000 tons lift been performed in April - May in Angola. Platform Lay-out and Installation Procedure The Benguela-Belize CPT platform comprised a 400 m high substructure and topsides facilities (Fig. 1). The substructure included a base section, foundation piles and two tower sections, with a total weight of 50,000 tons. The topsides included a Module Support Frame (MSF) with various topside modules weighing 35,000 tons. Installation of the Benguela-Belize Compliant Tower was split into two phases. The first phase, installation of the foundation section of the substructure, included the installation of the Levelling Piles Template (400t, dual crane), the Levelling Piles (310t each, dual crane upend), the Tower Base Template (3,100t, dual crane) and the Foundation Piles (1,000t each, dual crane upend).

Globally, the search for hydrocarbon is witnessing a dramatic shift from the land and swamp terrain to the offshore frontier with significant challenges in terms of technology requirements, safety, reliability and economics. The challenges become more apparent in offshore marginal fields where operators struggle with cutting edge technological demands, high CAPEX, lean reservoir and a possible poor return on investment (ROI). The last two decades have seen a huge increase in the application of subsea systems as the preferred concept for offshore production of oil and gas. Subsea is a term generally used to refer to equipment, technology, and methods employed to explore, drill, and develop oil and gas fields that exist below the sea bed. This paper explores the use of subsea production systems (SPS) as a possible solution to marginal field developments in West African waters. An SPS case study for marginal fields developed with a floating system is analysed and compared to other offshore development concepts from applicable equipment's, schedule to CAPEX and OPEX considerations.

The Akosombo strain of Nile tilapia is the only approved tilapia strain for culture in Ghana. In this study, exotic red tilapia suspected to be cultured in fish farms within the Lower Volta River Basin of the Lake Volta were collected for species identification based on their morphological features. A molecular screening using DNA barcoding sequencing was then performed on the samples targeting the cytochrome C oxidase subunit 1 mitochondrial gene ( COI ). Morphological characterization identified three taxa, predominantly red tilapia ( Oreochromis sp.), alongside Coptodon sp. and a single O. niloticus specimen. Phylogenetic analysis resolved two well‐supported clusters; one corresponding to native Ghanaian O. niloticus haplotypes and another comprising red tilapia lineages not naturally occurring in West African waters. The widespread occurrence of red tilapia, an introduced, hybridized domesticated strain not approved for aquaculture production in Ghana, strongly suggests intentional or accidental introduction of foreign broodstock. Their presence raises concerns regarding genetic introgression into native O. niloticus populations, including the locally important and approved Akosombo strain, as well as increased vulnerability to transboundary fish diseases. These findings highlight a significant breach in national biosecurity and stock management systems. Strengthened genetic monitoring, farmer education, hatchery regulation, import control enforcement, and structured breeding programs are urgently required to safeguard Ghana's aquaculture industry and conserve indigenous tilapia genetic resources.

FLUORINE absorption from drinking water during the period of calcification of the teeth has long been correlated with mottling of the dental enamel1. In East Africa the excessive amounts of fluorine in some drinking waters have become a matter for urgent consideration2; but little is known of fluorine distribution in West African waters.

Seabirds interact with fishing vessels to consume fishing discards and baits, sometimes resulting in incidental capture (bycatch) and the death of the bird, which has clear conservation implications. To understand seabird-fishery interactions at large spatiotemporal scales, researchers are increasing their use of simultaneous seabird and fishing vessel tracking. However, vessel tracking data can contain gaps due to technical problems, illicit manipulation, or lack of adoption of tracking monitoring systems. These gaps might lead to underestimating the fishing effort and bycatch rates and jeopardize the effectiveness of marine conservation. We deployed bird-borne radar detector tags capable of recording radar signals from vessels. We placed tags on 88 shearwaters (Calonectris diomedea, Calonectris borealis, and Calonectris edwardsii) that forage in the northwestern Mediterranean Sea and the Canary Current Large Marine Ecosystem. We modeled vessel radar detections registered by the tags in relation to gridded automatic identification system (AIS) vessel tracking data to examine the spatiotemporal dynamics of seabird-vessel interactions and identify unreported fishing activity areas. Our models showed a moderate fit (area under the curve >0.7) to vessel tracking data, indicating a strong association of shearwaters to fishing vessels in major fishing grounds. Although in high-marine-traffic regions, radar detections were also driven by nonfishing vessels. The tags registered the presence of potential unregulated and unreported fishing vessels in West African waters, where merchant shipping is unusual but fishing activity is intense. Overall, bird-borne radar detectors showed areas and periods when the association of seabirds with legal and illegal fishing vessels was high. Bird-borne radar detectors could improve the focus of conservation efforts.

We compare the performance of European Union (EU) and Chinese fisheries access agreements with West African countries in terms of illegal and unreported fishing, economic equity, and patterns of exploitation. Bottom-up re-estimations of catch reveal that the EU (1.6 million t•year-1) and China (2.3 million t•year-1) report only 29% and 8%, respectively, of their estimated total catches (including estimated discards whenever possible) from West African countries between 2000 and 2010. EU catches are declining, while Chinese catches are increasing and are yet to reach the historic maximum level of EU catches (3 million t•year-1 on average in the 1970s-1980s). The monetary value of EU fishing agreements, correlated in theory with reported catches, is straightforward to access, in contrast to Chinese agreements. However, once quantified, the value of Chinese agreements is readily traceable within the African economy through the different projects they directly cover, in contrast to the funds disbursed [to host governments] by the EU. Overall, China provides resources equivalent to about 4% of the ex-vessel value [value at landing] of the catch taken by Chinese distant-water fleets from West African waters, while the EU pays 8%. We address the difficulties of separating fees directly related to fishing from other economic or political motivations for Chinese fees, which could introduce a bias to the present findings as this operation is not performed for EU access fees officially related to fishing. Our study reveals that the EU and China perform similarly in terms of illegal fishing, patterns of exploitation and sustainability of resource use, while under-reporting by the EU increases and that by China decreases. The EU agreements provide, in theory, room for improving scientific research, monitoring and surveillance, suggesting a better performance than for Chinese agreements, but the end-use of the EU funds are more difficult, and sometime impossible to ascertain.

In 1934, Stiasny described cubomedusan specimens from Station 279 of the Discovery Expedition 1925–27 in the Gulf of Guinea, West Africa as Tamoya haplonema. He also presented line drawings of the habitus that raised some doubts on the identification of the species. In the collections of the Natural History Museum of London, the described specimens were still available and in good condition due to their storage in formalin. More specimens could be found in other European museums. The formalin made a genetic analysis impossible but as all anatomical structures were excellently preserved, a direct comparison was possible with the structures in Tamoya haplonema and Tamoya ohboya from the Americas. Due to the morphological comparison with the American Tamoya species it could be confirmed that the African Tamoya specimens are an up-to-now undescribed new Tamoya species, Tamoya anacamori sp. nov., described herein.