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Diet of Cape fur seals Arctocephalus pusillus pusillus at three mainland breeding colonies in Namibia. 2. Temporal variation
Abstract and Figures
Scat analysis was used to assess temporal variability in
the diet composition of Cape fur seals Arctocephalus
pusillus pusillus from three breeding colonies in
Namibia (January 1994 to April 2002). The diet displayed
significant inter- and intra-annual variation in composition
at each of the study colonies. The diet was not
predictable on an annual pattern, and little consistent
seasonality was apparent at each of the study sites.
However, some prey species tended to display some
seasonality, possibly as a result of their life-history
patterns. At the Cape Cross colony, small Cape hake
Merluccius spp. in the diet coincided with their spawning
season. At the Atlas-Wolf Bay and Van Reenen Bay
colonies, lanternfish Lampanyctodes hectoris were
most prevalent in the diet during the upwelling season
(August–January). Outside that period, pelagic goby
Sufflogobius bibarbatus were most abundant in the diet
at those colonies. This pattern may be a result of the
gobies’ southwards migration from northern Namibian
waters where smaller goby are dominant in the diet at
the Cape Cross colony in the upwelling season. The
prevalence of Cape horse mackerel Trachurus trachurus
capensis in the diet at Cape Cross was coincident
with the pelagic phase of juvenile horse mackerel.
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... The species comprises a major proportion of southern Africa's marine predator biomass, previously estimated to consume ca. 2 million tonnes of prey per year (Punt et al. 1995). While Cape fur seals are generalist feeders, the bulk of their diet consists of commercially important species such as sardine Sardinops sagax, anchovy Engraulis encrasicolus, Cape horse mackerel Trachurus trachurus capensis, hake (Merluccius spp.), West Coast rock lobster Jasus lalandii and chokka squid Loligo vulgaris reynaudii (de Bruyn et al. 2003, Mecenero et al. 2006a,b, Huisamen et al. 2012, Connan et al. 2014. The composition of their diet also varies both spatially (David 1987, de Bruyn et al. 2003, Mecenero et al. 2006a) and temporally (de Bruyn et al. 2005, Mecenero et al. 2006b). ...
... While Cape fur seals are generalist feeders, the bulk of their diet consists of commercially important species such as sardine Sardinops sagax, anchovy Engraulis encrasicolus, Cape horse mackerel Trachurus trachurus capensis, hake (Merluccius spp.), West Coast rock lobster Jasus lalandii and chokka squid Loligo vulgaris reynaudii (de Bruyn et al. 2003, Mecenero et al. 2006a,b, Huisamen et al. 2012, Connan et al. 2014. The composition of their diet also varies both spatially (David 1987, de Bruyn et al. 2003, Mecenero et al. 2006a) and temporally (de Bruyn et al. 2005, Mecenero et al. 2006b). Although the diet of Cape fur seals has been relatively well researched, surprisingly little is known about their foraging behaviour, including horizontal and vertical utilisation of the marine environment. ...
... Although previously considered to be a predominantly epipelagic forager in the highly productive Benguela, the diving behaviour of some individuals appears more similar to that of benthic foraging Australian fur seals in the less productive Bass Strait (Arnould & Kirkwood 2007, Kirkwood & Arnould 2011. Previous diet records suggest that benthic prey have always comprised at least some proportion of Cape fur seal diet in the Benguela (de Bruyn et al. 2003, Mecenero et al. 2006a. Despite this, the drivers of benthic foraging, as well as its ecological implications, remain unclear and warrant further investigation possibly spanning several years. ...
Knowledge of animal foraging behaviour has implications for management and conservation. While Cape fur seals Arctocephalus pusillus pusillus comprise a major proportion of the southern African marine predator biomass, little is known about their at-sea movements. We investigated foraging distribution, habitat use and diving behaviour for 35 adult female Cape fur seals from 3 breeding colonies experiencing contrasting oceanographic regimes. Animals from Black Rocks, the smallest and eastern-most colony, undertook shorter foraging trips and utilised shallower waters over the shelf. In comparison, animals from the larger west coast colonies, at Kleinsee and False Bay, travelled further and utilised deeper shelf and shelf-slope waters. However, across colonies, females typically preferred depths of <500 m and slopes of <5°. Kleinsee and False Bay seals selected sea surface temperatures within the range typically preferred by pelagic prey species such as round herring, sardine and anchovy (14-19°C). Black Rocks individuals showed bimodal preferences for colder (16°C) and warmer waters (>22°C). Dive behaviour was similar between Kleinsee and False Bay individuals (unavailable from Black Rocks), with both pelagic and benthic foraging evident. Diel patterns were apparent at both sites, as dive depth and benthic diving increased significantly during daylight hours, likely reflecting vertical movements of prey species. We provide the first assessment of Cape fur seal movement behaviour for the South African component of the population. Observed geographic differences likely reflect the availability of suitable habitat but may also indicate differences in foraging strategies and density-dependent effects throughout the range of this species.
... The Cape fur seal (CFS) Arctocephalus pusillus pusillus is the largest fur seal subspecies and is endemic to southern Africa, with breeding colonies extending from Ilha dos Tigres in Angola to Algoa Bay in South Africa (Kirkman et al. 2013). The CFS is an important marine apex predator in the Benguela region, feeding on a combination of pelagic and benthic species, and occasionally birds (Mecenero et al. , 2006a(Mecenero et al. , 2006bMakhado et al. 2006Makhado et al. , 2013Connan et al. 2014). Their distribution usually coincides with regions that sustain profitable fisheries (Croll and Tershy 1998;Duarte et al. 2005;Mecenero et al. 2006a), and the subspecies has been estimated to consume approximately two million tonnes of fish per annum (Butterworth et al. 1995). ...
... The CFS is an important marine apex predator in the Benguela region, feeding on a combination of pelagic and benthic species, and occasionally birds (Mecenero et al. , 2006a(Mecenero et al. , 2006bMakhado et al. 2006Makhado et al. , 2013Connan et al. 2014). Their distribution usually coincides with regions that sustain profitable fisheries (Croll and Tershy 1998;Duarte et al. 2005;Mecenero et al. 2006a), and the subspecies has been estimated to consume approximately two million tonnes of fish per annum (Butterworth et al. 1995). Fishers have attributed most of the blame to CFS when there has been a decline in catches (Wickens et al. 1992). ...
... Many studies have examined the diet composition of the CFS within southern Africa (de Bruyn et al. 2005;Mecenero et al. 2006aMecenero et al. , 2006bHuisamen et al. 2012;Connan et al. 2014). The research suggests that the diet comprises a wide range of marine fishes and cephalopods and even seabirds. ...
The population of Cape fur seal Arctocephalus pusillus pusillus at Ilha dos Tigres off the coast of southern Angola is expanding. Until now the only available biological information on the population has been its demographic parameters, and this insufficiency has hindered our understanding of the population’s ecology. The current study aimed to describe the diet of this northernmost population of the subspecies, based on a once-off sampling opportunity. The diet was described using scat analysis and hard-part identification from scats collected in July 2014. Small pelagic fishes (Trachurus spp., Engraulis encrasicolus and Sardinops sagax) were the numerically dominant prey items, conforming with the findings of studies conducted on other Cape fur seal colonies. Although not numerically dominant, cephalopods were dominant in terms of mass.
... Individuals displayed diel variation, diving to shallower depths at night and reaching the deepest recorded dives for females of any fur seal species during daylight hours (ca 450 m). These findings are consistent with previously published reports of the Cape fur seal diet from the Benguela comprising primarily schooling fish [18,22,71] and highlight the potential negative consequences of environmental changes affecting the distribution of such prey [72] on foraging effort for the population. Figure 6. ...
... The limited previously available information on the diving behaviour ( [25]; SFRI, unpublished data for a few individuals in 1994-1997), and extensive diet studies (e.g. [18,20,71]), of the Cape fur seal have suggested that it is primarily an epipelagic forager. This is consistent with its distribution being largely associated with the Benguela, an area characterized by very high marine primary productivity supporting a large biomass of small pelagic prey species [35,94,95] conducive to mid-water foraging by air-breathing marine vertebrates [96]. ...
... Both gobies and lanternfish were found to be prominent in the previously sardine-dominated diet of Cape fur seals in Namibia following the 1970s stock collapse of sardines in the northern Benguela [20,71,92]. Therefore, the observed occurrence of benthic and mesopelagic foraging in the present study could reflect inadequate pelagic prey availability [96]. ...
While marine top predators can play a critical role in ecosystem structure and dynamics through their effects on prey populations, how the predators function in this role is often not well understood. In the Benguela region of southern Africa, the Cape fur seal (Arctocephalus pusillus pusillus) population constitutes the largest marine top predator biomass, but little is known of its foraging ecology other than its diet and some preliminary dive records. Dive information was obtained from 32 adult females instrumented with dive recorders at the Kleinsee colony (29°34.17 0 S, 16°59.80 0 E) in South Africa during 2006-2008. Most dives were in the depth range of epipelagic prey species (less than 50 m deep) and at night, reflecting the reliance of Cape fur seals on small, vertically migrating, schooling prey. However, most females also performed benthic dives, and benthic diving was prevalent in some individuals. Benthic diving was significantly associated with the frequency with which females exceeded their aerobic dive limit. The greater putative costs of benthic diving highlight the potential detrimental effects to Cape fur seals of well-documented changes in the availability of epipelagic prey species in the Benguela.
... There are 15 breeding and 4 non-breeding Cape fur seal (Arctocephalus pusillus pusillus) colonies along the Namibian coast (De Villiers et al., 1997). According to Mecenero et al. (2006) who wrote on the spatial distribution of the diets of seals, there are two main areas of seal aggregations: Cape Cross (21°47'S and 13°57'E, with 187,000 seals in 2001) and Lüderitz (Van Reenen Bay, Atlas Bay and Wolf Bay, south of Lüderitz, around 27°S and 15°E, with 173,000 seals in 2001). These two areas and the 200 km forage range around them were classified as essential habitat for seals (Mecenero et al., 2006). ...
... According to Mecenero et al. (2006) who wrote on the spatial distribution of the diets of seals, there are two main areas of seal aggregations: Cape Cross (21°47'S and 13°57'E, with 187,000 seals in 2001) and Lüderitz (Van Reenen Bay, Atlas Bay and Wolf Bay, south of Lüderitz, around 27°S and 15°E, with 173,000 seals in 2001). These two areas and the 200 km forage range around them were classified as essential habitat for seals (Mecenero et al., 2006). Hampton (2003) gave numbers of seals extrapolated from the aerial pup sensus, which showed that there were smaller hallouts for seals at Cape Frio and between Sandwich Harbour and Sylvia Hill not shown by Mecenero et al. (2006). ...
... These two areas and the 200 km forage range around them were classified as essential habitat for seals (Mecenero et al., 2006). Hampton (2003) gave numbers of seals extrapolated from the aerial pup sensus, which showed that there were smaller hallouts for seals at Cape Frio and between Sandwich Harbour and Sylvia Hill not shown by Mecenero et al. (2006). Seals are therefore prevalent in the Skeleton Coast Park and the West Coast Recreational Area of the spatial model. ...
... Long-term research on the diet of Cape fur seals Arctocephalus pusillus pusillus has shown that their diet in Namibia has changed dramatically over the past few decades due to changes in prey availability (Mecenero et al. 2006b,c), notably the collapse of the sardine fishery in the 1970s (Utne-Palm et al. 2010, Cedras et al. 2011, van der Bank et al. 2011. This collapse caused an increase in abundance of S. bibarbatus and T. t. capensis which became more prevalent in the diet of seals (Mecenero et al. 2006c). In addition, the diet of Cape fur seals at colonies in central Namibia differs greatly from those in southern Namibia, which has been correlated with spatial differences in prey availability between those areas (Mecenero et al. 2006b). ...
Defining the trophic relationships of marine predators and their dietary preferences is essential in understanding their role and importance in ecosystems. Here we used stable isotope analysis of skin samples (δ ¹⁵ N values reflecting trophic level and δ ¹³ C values reflecting foraging habitat) to investigate resource partitioning and spatial differences of the feeding ecology of dusky dolphins Lagenorhynchus obscurus and Heaviside’s dolphins Cephalorhynchus heavisidii from 2 coastal study sites separated by 400 km along the coast of central (Walvis Bay) and southern (Lüderitz) Namibia in the Benguela upwelling ecosystem. Overall, isotopic niches of both predators were significantly different, indicating partitioning of resources and foraging habitats. Despite their smaller body size, Heaviside’s dolphins fed at a significantly higher trophic level than dusky dolphins. Stable isotope mixing models revealed that both species fed on high trophic level prey (i.e. large Merluccius spp., large Sufflogobius bibarbatus , and Trachurus t. capensis ) at Walvis Bay. The diet of both dolphin species included smaller pelagic fish and squid at Lüderitz. Spatial differences highlight that Heaviside’s and dusky dolphins may exhibit dietary plasticity driven by prey availability, and that they likely form distinct population segments. Important prey for both dolphin species, specifically Merluccius spp. and T. t. capensis , are the main target of trawl fisheries in the Benguela upwelling ecosystem, highlighting potential resource overlap between dolphins and fisheries.
... After the collapse of the sardine population Sardinops sagax, S. bibarbatus has partially replaced the sardine as the main prey item in the diet of predators, where it can represent over 50% of the prey consumed by seabirds, seals and hake Merluccius spp. (Crawford, Cruickshank, Shelton, & Kruger, 1985;Crawford et al., 1987;van der Lingen et al., 2006;Mecenero, Roux, Underhill, & Kirkman, 2006;. As a result, it has become vital to understand their population genetic structure across the region. ...
The bearded goby Sufflogobius bibarbatus is an abundant endemic small fish species on the continental shelf of the northern Benguela. The goby habitat is characterised by generally low bottom oxygen concentrations that vary spatially and seasonally. In the present study of population structure, 13 samples of S. bibarbatus from inner and outer shelf areas between 19°S and 32°S were screened using ten microsatellite loci. The genetic data were analysed in relation to isolation by distance and depth. Furthermore, for the first time, this study examined genetic data in relation to bottom oxygen concentration at the sampling locations. The data show low but significant genetic heterogeneity (G‐test; FST = 0.007, p < .05). There was weak but significant genetic differentiation along a latitudinal gradient across all sampling sites from 19.50°S to 32.37°S (Mantel test; r = .464, p = .001), but this disappeared when the southernmost sample was removed. On the other hand, a positive correlation of bottom oxygen concentration with pairwise FST (r = .336; p = .017) was observed among the sampling sites from the Northern Benguela shelf area. Overall, the data are complex but suggest that isolation by distance and bottom oxygen concentration may play a role in the genetic structuring of S. bibarbatus. The findings are discussed in relation to the species’ life history features and oceanographic characteristics of the Benguela upwelling ecosystem.
... Sufflogobius bibarbatus has partially replaced S. sagax as the main prey item in the diet of predators, where it can represent over 50% of the prey consumed by seabirds, seals and Merluccius spp. (Crawford et al., 1985Mecenero et al., 2006;van der Lingen et al., 2006;Ludynia et al., 2010;Fig. 2). ...
The oceans of the world are slowly losing oxygen, in part because of climate change and in part because of anthropogenic eutrophication. This deoxygenation affects marine organisms in species-specific ways. This paper reviews what is known on how hypoxia tolerant species respond to low dissolved oxygen, using the bearded goby Sufflogobius bibarbatus as a model system. This species is endemic to the Benguela upwelling ecosystem, where, off Namibia, 9000 km² of the shelf is hypoxic. Here, the species is now considered central to ecosystem functioning and in recent decades it has sustained commercial fisheries. Unlike their predators, S. bibarbatus has strong anti-predator responses as they can remain alert and escape threats in anoxic and severely hypoxic waters and can cope with sulphide shocks. Populations display diel vertical migration and shuttle between suboxic seabed refugia during the day to more oxygenated waters higher up in the water column at night and whilst they may share the water column with predators they may reduce their predation risk by associating with jellyfish (Aequorea forskalea and Chrysaora fulgida). The spatial distribution of S. bibarbatus varies with changes in available oxygen and populations expand and contract with climate-induced changes in the distribution of hypoxic waters. This species has an unusual diet and plays an important role in ecosystem functioning. It is a batch-spawner, with a protracted spawning season. Remarkably, males display alternative reproductive tactics and reproduction can take place at oxygen levels <0·5 ml l⁻¹ dissolved oxygen on the shelf break. Gaps in knowledge are identified and future works are proposed.
... Fur seals have been reported to have a tendency to feed in deep water beyond the continental shelf on small squid and fish (Gentry 2009). However, e.g. the South African fur seal (Artocephalus pusillus) feeds opportunistically mainly on teleosts, on rare occasions more than 1 m in length (Mecenero et al. 2006), as well as on seabirds (Mecenero et al. 2005). The only member of the family of walruses, the walrus (Odobenus rosmarus), feeds on all kinds of benthic invertebrates, predominantly bivalves (Fay 1982). ...
Marine mammals often forage in dark and turbid waters. While dolphins use echolocation under such conditions, pinnipeds seem to lack this sensory system. Instead, species of the families Phocidae (true seals) and Otariidae (eared seals) both possess richly innervated whiskers (synonymously “vibrissae”) representing highly sensitive hydrodynamic receptors that enable these animals to detect fish-generated water movements. The third family of pinnipeds, the Odobenidae (walruses), is less well studied. As water movements in the wake of fishes persist for several minutes, they constitute hydrodynamic trails that should be trackable by piscivorous predators. Hydrodynamic trail following has indeed been shown for the harbor seal (Phoca vitulina) and the California sea lion (Zalophus californianus). However, in experiments with a sea lion aging of the trails resulted in an earlier decrease in performance. This difference in tracking performance most likely is due to differences in the structure of the respective vibrissal hair shaft. In the harbor seal the high sensitivity and excellent tracking performance is ascribed to the specialized undulated structure of the whiskers that largely suppresses self-generated noise in the actively moving animal. In contrast, the whiskers of a swimming California sea lion, which are smooth in outline, are substantially affected by self-generated noise. However, in the sea lion such self-generated noise contains a characteristic carrier frequency that might allow hydrodynamic reception by being modulated in response to hydrodynamic stimuli impinging on the hair. Thus, in the course of pinniped evolution at least two types of whiskers evolved that realized different mechanisms for the reception of external hydrodynamic information.
I have analysed 1 295 of the outputs published by the South African Marine Science Community (SAMSC) in either peer-reviewed journals or as books/book chapters for the period 2001-2006, with a view to identifying trends in the field, summarizing institutional overlaps and assessing the demographic state-of-play. Although almost 70% of our outputs were published internationally, we published the bulk of our research in strictly marine science journals which suggests, perhaps, that we need to be thinking bigger. More than 22% of all outputs were led by International colleagues, and these were published in journals with a significantly higher Impact Factor than those led by local authors. Women led less than 25%, and persons from previously disadvantaged backgrounds led less than 10%, of all outputs: this needs monitoring, discussion and pro-active response by employers. Thirty-six authors (~95% male, ~97% white) were responsible for more than 50% of all outputs, which suggests that the field is not totally dominated by an ageing cohort. Despite the fact that the bulk of the SAMSC is centred in the SW Cape, our study areas are approximately equally spread around the coastline, though there is an obvious institutional bias to the geographical location of study sites. Globally-orientated studies were generally published in " better " outlets than locally-orientated work, and were more likely to be led by international colleagues. There was a disappointing amount of work conducted in other African states, and indeed, we published more work from the Southern Oceans than from our (even) immediate neighbours, indicating that perhaps were not playing as much of a role within the region as we could. Little of our work is being conducted in habitats that have been defined as threatened and studies in coral reefs or rocky reefs and in demersal environments are perhaps particularly needed. Vertebrates continue to be better studied than 1 The article should be cited as: Gibbons, M.J. (2009). A biologists' personal overview of the SA Marine Science community and its outputs (2001-2006). Unsolicited Report to SANCOR, pp 1-126.
Changes that occurred in sea surface and some deeper temperatures, surface winds, currents, plankton and some dominant crustacean (rock lobster Jasus lalandii), molluscan (squid Loligo vulgaris reynaudii and abalone Haliotis midae), fish (anchovy Engraulis capensis, pilchard Sardinops ocellatus, Cape hakes Merluccius spp., sole Austroglossus pectoralis, kingklip Genypterus capensis and various species of linefish) and seabird (Cape gannet Morus capensis) resources in the Benguela ecosystem in the 1980s are documented. Although fishing had a clear influence on changes in some of the resources, a wide spectrum of organisms, from plankton to top predators, were influenced directly or indirectly by the abiotic environment. Concurrent changes in many of the resources suggest that the same environmental change may impact on more than one. Simultaneous change throughout the Benguela system indicates that environmental forcing sometimes takes place over wide geographic areas. At the northern and southern extremities of the Benguela system, responses to environmental change may be different because processes through which the change is mediated are different.
There are two types of interactions between seals and commercial fisheries in South Africa: biological (potential competition for shared resources between the two "predators") and operational (conflicts during fishing operations). Using data for the 1980s, a comparison is made of relative consumption by different predators in South African waters. Seals and fisheries are not the major consumers in the system, but they do take comparable amounts. This has resulted in calls for a reduction in the seal population, but to date, no studies have shown that reducing seal predation of commercial species will make more fish available for the fisheries. Most fisheries are subject to some form of operational interaction with seals. These interactions include consumption of catches (operational consumption), disturbance of fishing operations (operational disturbance) and damage to fishing gear (operational gear damage); they vary in degree of severity, both seasonally and regionally. Estimates of the consumption by seals from fishing operations in South Africa show it to be a minimal percentage of fishery catches and a small proportion of the total predation by seals. Preliminary calculations of overall economic losses resulting from seal interference show this to be small in comparison with the wholesale value of the catches. Seals die as a result of fishing operations, and estimates of the potential mortality through entanglement, drowning and deliberate killing indicate this mortality to be of a magnitude that should be monitored.
We studied the dietary preferences of Antarctic fur seals Arctocephalus gazella from Cap Noir, Iles Kerguelen, foraging in the Antarctic Polar Frontal Zone (PFZ) in February of 1998, 1999 and 2000. Scats were collected and analyzed for remaining prey hard parts in each of the 3 years, and in 1999 and 2000, the fatty acid (FA) composition of fur seal milk samples was also examined for longer-term dietary preferences. Scat analyses revealed that seals foraged primarily on fish and some squid in all 3 years with 25 species of fish being taken during the study. Myctophid fish accounted for an average of 94% by number of all fish consumed with 3 species, Gymnoscopelus nicholsi, G. piabilis and Electrona subaspera, forming the core diet. Inter-annual differences in dietary species composition were apparent, however, with the presence of the mackerel icefish Champsocephalus gunnari in 1998 and the myctophid Protomyctophum tenisoni in 1999 accounting primarily for the differences observed between years. While reconstituted prey biomass per scat was similar between years, scats from 1998 represented less energy per gram than those from 1999 and 2000. This study highlights the usefulness of using FA signature analysis to confirm longer-term shifts in dietary intake of fur seals using milk samples. Polyunsaturated fatty acids (PUFAs) were significantly more prevalent in the 1999 milk samples, which were also lower in overall lipid content (43% vs 53%). G. nicholsi, a particularly oily fish, occurred in higher proportions in the diet in 2000, perhaps explaining the higher incidence of monounsaturated fatty acids (MUFAs) in this year and the generally higher lipid levels present in milk samples. The inter-annual variation in the diet of Antarctic fur seals confirmed by these 2 techniques lends support to the hypothesis that previously identified variations in oceanographic conditions surrounding lies Kerguelen in 1998, 1999 and 2000 affect the availability of fur seal prey resources.
Pelagic gobies Sufflogobius bibarbatus were numerically the most important prey of jackass penguins Spheniscus demersus. Cape cormorants Phalacrocorax capensis and bank cormorants P. neglectus sampled at islands off the South West African coast during the period 1978–1982. These three seabirds feed on small gobies near the surface and some of them can also dive sufficiently deep to catch larger gobies. Their populations at islands north of Lüderitz, where gobies are abundant, have been increasing. Cape gannets Morus capensis feed only on large gobies that are infrequently at the surface, and the gannet population off South West Africa has shown a large decrease since the collapse of the pilchard Sardinops ocellata resource in the late 1960s and early 1970s. In the intense perennial upwelling system situated between 22 and 27°S gobies are believed to have partially replaced pilchards during the 1970s. Both pilchards and gobies are able to feed on large diatoms of the genera Chaetoceros and Delphineis, which dominated the inshore phytoplankton in the early 1970s when biomass levels of both pilchards and gobies were low.
The diet composition of the Cape fur seal Arctocephalus pusillus pusillus off the west coast of South Africa was determined using the volumetric method from samples collected at sea between 1984 and 1990. Data were stratified spatially and temporally and an attempt was made to exclude from the analysis seals which probably scavenged from trawlers. Teleost fish made up the bulk of the diet, but cephalopods were also important. The results for individual strata were highly variable, but they suggest that young Mercluccius capensis contributed some 5–30% of the diet, whereas the fraction of M. paradoxus in the diet was roughly 0–30%. However, if seals feed predominantly inshore and during the day, then the hake p0l1ion of the diet would consist almost exclusively of the inshore M. capensis.
The myctophid Lampanyctodes hectoris is caught by purse-seiners in the Benguela ecosystem off southern Africa. Ichthyoplankton surveys indicate peak spawning in late winter/spring, with eggs and larvae concentrated offshore of the 200 m isobath. Fecundity ranges from 572 to 1431 eggs·g−1 wet body mass, and gonadal activity is confined to a few months of the year, peaking in July and August. The sternoptychid Maurolicus muelleri is not fished commercially in the Benguela ecosystem, but its eggs and larvae are present throughout the year, with a maximum in summer and a lesser peak in winter. Maximum egg abundance follows the 200 m isobath in water of surface temperature 12,75–15,45°C. Its fecundity ranges from 161 to 738 eggs·g−1 and gonads are active during all months, suggesting a more prolonged spawning season than for L. hectoris.