The Impact of Predation by Marine Mammals on Patagonian Toothfish Longline Fisheries

<p>The Messinian Salinity Crisis (MSC) was the greatest paleoenvironmental perturbation the Mediterranean has ever seen. The literature is abundant in hypotheses on the repercussions of the MSC on organisms. However, all these are based on incomplete and still uncertain scenarios about the MSC evolution, as well as on the assumption that such a paleoenvironmental perturbation must have completely reset marine biota. Having prevailed for many decades now, this assumption has leaked from paleontology and geosciences to biological sciences, with numerous studies taking this scenario for granted instead of using it as a starting hypothesis to be tested. Here, we review and revise the marine fossil record across the Mediterranean from the Tortonian until the Zanclean to follow the current rules of nomenclature, correct misidentifications, and control for stratigraphic misplacements. We examine the composition of marine faunas, both taxonomically and considering the function of each group in the marine ecosystem and the transfer of energy through the marine food web. Specifically, we investigate the following functional groups: 1) primary producers, 2) secondary producers, 3) primary consumers, 4) secondary consumers, and 5) top predators. Our study includes sea grasses, phytoplankton, corals, benthic and planktonic foraminifera, bivalves, gastropods, brachiopods, echinoids, bryozoans, fishes, ostracods, and marine mammals. We calculate biodiversity indexes to provide independent evidence quantifying to what degree the marine fauna underwent:</p><ol><li>A drop of overall regional biodiversity of the Mediterranean due to environmental stress during the Messinian.</li> <li>A taxonomic and functional change between the Tortonian, Messinian, and the Zanclean, that is before and after the MSC, as well as during the precursor events to that actual crisis taking place after the Tortonian/Messinian boundary.</li> <li>The onset of the present-day west-to-east decreasing gradient in species richness, which has been related to the sea temperature and productivity gradients and the distance from the Gibraltar connection to the Atlantic.</li> </ol>

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Managing the Impacts of Human Activities on Fish Habitat: The Governance, Practices, and Science

Managing the Impacts of Human Activities on Fish Habitat: The Governance, Practices, and Science ◽

10.47886/9781934874417.ch4 ◽

2015 ◽

Keyword(s):

Benthic Invertebrates ◽

Marine Mammals ◽

Fish Habitat ◽

Fishing Gear ◽

Governance Practices ◽

Coexisting Species ◽

The Government ◽

The Impact ◽

Poor Infrastructure ◽

Technical Measures

<em>Abstract.</em>—Mexico is an important producer of fish resources, contributing 1.5% to the total world production. However, most of the fisheries are overexploited or fished to the maximum sustainable level as a result of problems such as overexploitation, poor infrastructure, poaching, limited knowledge of fishing laws, high discard rates, weak fisheries institutions, and little ability to research and manage these difficulties. To solve these problems, the National Program of Fisheries and Aquaculture was established in order to achieve sustainability in Mexican fisheries with the participation of the government, the fishing industry and research institutions. The program has been implemented for the 22 main fisheries of the country, notably the tuna, shrimp and shark fisheries, for which technical measures have been implemented for controlling the catch, the effort and the impact on coexisting species. Specifically, these measures have been aimed at reducing the bycatch of marine mammals and turtles, demersal and benthopelagic fishes and benthic invertebrates. Also, measures have been implemented to mitigate impacts of fishing gear on the benthos and coral reefs. However, many issues still need to be resolved both for these and other lower revenue fisheries, which are important in terms of their effect on ecosystems.

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NEPA, National Security, and Ocean Noise: The Past, Present, and Future of Regulating the Impact of Navy Sonar on Marine Mammals

Journal of International Wildlife Law & Policy ◽

10.1080/13880292.2010.524588 ◽

2010 ◽

Vol 13 (4) ◽

pp. 326-356

Author(s):

Randall Abate

Keyword(s):

National Security ◽

Marine Mammals ◽

The Past ◽

Ocean Noise ◽

The Impact

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Epidemiological models to control the spread of information in marine mammals

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.2037 ◽

2016 ◽

Vol 283 (1844) ◽

pp. 20162037 ◽

Cited By ~ 6

Author(s):

Zachary A. Schakner ◽

Michael G. Buhnerkempe ◽

Mathew J. Tennis ◽

Robert J. Stansell ◽

Bjorn K. van der Leeuw ◽

...

Keyword(s):

Marine Mammals ◽

Foraging Behaviour ◽

Social Transmission ◽

Sea Lion ◽

California Sea Lions ◽

Sea Lions ◽

Promising Tool ◽

Diffusion Analysis ◽

And Control ◽

The Impact

Socially transmitted wildlife behaviours that create human–wildlife conflict are an emerging problem for conservation efforts, but also provide a unique opportunity to apply principles of infectious disease control to wildlife management. As an example, California sea lions ( Zalophus californianus ) have learned to exploit concentrations of migratory adult salmonids below the fish ladders at Bonneville Dam, impeding endangered salmonid recovery. Proliferation of this foraging behaviour in the sea lion population has resulted in a controversial culling programme of individual sea lions at the dam, but the impact of such culling remains unclear. To evaluate the effectiveness of current and alternative culling strategies, we used network-based diffusion analysis on a long-term dataset to demonstrate that social transmission is implicated in the increase in dam-foraging behaviour and then studied different culling strategies within an epidemiological model of the behavioural transmission data. We show that current levels of lethal control have substantially reduced the rate of social transmission, but failed to effectively reduce overall sea lion recruitment. Earlier implementation of culling could have substantially reduced the extent of behavioural transmission and, ultimately, resulted in fewer animals being culled. Epidemiological analyses offer a promising tool to understand and control socially transmissible behaviours.

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Modeling as a complementary tool to acoustic data for understanding the impact of environmental disasters on marine mammals

The Journal of the Acoustical Society of America ◽

10.1121/1.5014255 ◽

2017 ◽

Vol 142 (4) ◽

pp. 2533-2533

Author(s):

Azmy S. Ackleh ◽

Ross Chiquet ◽

Tingting Tang ◽

Amy Veprauskas ◽

Hal Cawell ◽

...

Keyword(s):

Marine Mammals ◽

Acoustic Data ◽

Environmental Disasters ◽

The Impact

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The economic cost of seabird bycatch in Argentinean longline fisheries

Bird Conservation International ◽

10.1017/s0959270911000219 ◽

2011 ◽

Vol 22 (1) ◽

pp. 59-65 ◽

Cited By ~ 7

Author(s):

PATRICIA GANDINI ◽

ESTEBAN FRERE

Keyword(s):

Economic Cost ◽

High Rate ◽

Mitigation Measures ◽

Economic Losses ◽

Fishing Vessels ◽

Order Of Magnitude ◽

Patagonian Toothfish ◽

Catch Rates ◽

Longline Fisheries

SummarySeabird mortality in longline fisheries is believed to be an important cause of the reductions in many seabird populations worldwide, and results in reduced fishing efficiency and economic losses for fishing companies. We estimated the economic cost of not using seabird bycatch deterrents in Argentinean longline fisheries, with the intention of encouraging adoption of mitigation measures in those fisheries. We conducted the study in the Argentine ling Genypterus blacodes and Patagonian toothfish Dissostichus eleginoides fisheries from 2001 to 2006 on three fishing vessels. Data on the incidence of seabird bycatch were collected by seabird observers specially trained in seabird identification and data on the catch rates of target species, cost of bait and fish were provided by the fishing company, supervised by Federal Inspectors from the Provincial Fisheries Agency. To estimate the bait loss, we set lines both with and without the use of deterrents (streamer lines, night setting and strategic discharge of offal) in both fisheries. Seabird bycatch varies temporally and geographically, so to estimate economic losses using deterrents in each fishery, we used different bycatch rates/1000 hooks registered for different periods and fishing areas. Bycatch rates in the absence of deterrents were two birds/1000 hooks and 1.53 birds/1000 hooks for the Patagonian toothfish and ling fisheries, respectively. These rates equate to the loss of more than 1.5 and 2 million dollars over a 10 year period for each fishery. When estimations are made with lower mortality rates, economic losses declined abruptly and were in the order of hundreds of dollars/fishing trip, for the same period of time. Results show that using deterrents, long term profits for the fishing company increase at a considerably high rate (the decrease in monetary loss is an order of magnitude), and the mortality of seabirds decreases by the same proportion (CPUE of seabirds decreases from tens of thousands to a few hundred). In these fisheries, the use of mitigation measures that reduce bait loss and seabird mortality represents a win-win situation with benefits to conservation and fishing companies.

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Analysis of marine mammal bycatch in the Uruguayan pelagic longline fishery operating in the Southwestern Atlantic Ocean

ICES Journal of Marine Science ◽

10.1093/icesjms/fsu250 ◽

2015 ◽

Vol 72 (5) ◽

pp. 1637-1652 ◽

Cited By ~ 6

Author(s):

Cecilia Passadore ◽

Andrés Domingo ◽

Eduardo R. Secchi

Keyword(s):

Atlantic Ocean ◽

Marine Mammals ◽

Population Decline ◽

Additive Models ◽

Longline Fishery ◽

Southwestern Atlantic ◽

Southwestern Atlantic Ocean ◽

Pelagic Longline Fishery ◽

The Impact ◽

Pelagic Longline

Abstract Bycatch is one of the main causes of human-caused mortality and population decline of many marine mammals. Monitoring bycatch is the first step to understand the impact of the fisheries on the species affected. Understanding how the interaction between marine mammals and fishing operations varies in space and time, and how it is influenced by environmental variables, is essential for designing mitigation strategies to reduce bycatch mortality. In this paper, we use data gathered by scientific observers and a fishing skipper to analyse marine mammals bycatch by the Uruguayan pelagic longline fishery operating in the Southwestern Atlantic Ocean from 1996 to 2007. The total bycatch per unit effort (Bcpue) was 0.0150 marine mammals/1000 hooks and the highest values (∼0.2) were recorded between 37°–38°S and 49°–51°W. Total cetacean Bcpue during the study period was low (0.0051 cetacean/1000 hooks) and occurred between 32°–37°S and 46°–54°W. Generalized additive models showed that cetaceans' bycatch was mainly affected by the depth, sea surface temperature, and season. Although cetaceans were captured year-round, the highest values were registered in spring months, most bycatch events occurred over the continental slope (median = 619 m) and in waters with a median temperature of 19.7°C. The bycatch of pinnipeds was influenced by depth, location, and season. Pinniped bycatch occurred mainly in winter, in waters ranging from 80 to 5000 m of depth (median = 2366 m) between 34°–37°S (median = 35.9°S) and 54°–49°W (median = 51.8°W). The spatial analysis showed that most bycatch events occurred within the Brazil–Malvinas Confluence zone, an area of high productivity where the pelagic longline fleet concentrates its fishing effort and where marine mammals probably concentrate to feed.

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Blunt trauma observed in a common dolphin delphinus sp. Likely caused by a vessel collision in the Hauraki Gulf, New Zealand.

Pacific Conservation Biology ◽

10.1071/pc130019 ◽

2013 ◽

Vol 19 (1) ◽

pp. 19 ◽

Cited By ~ 13

Author(s):

E Martinez ◽

K A Stockin

Keyword(s):

Spinal Cord ◽

New Zealand ◽

Public Education ◽

Marine Mammals ◽

Vertebral Column ◽

Common Dolphin ◽

Post Mortem ◽

Immature Male ◽

Blunt Force Trauma ◽

The Impact

While coastal cetaceans can become habituated to watercraft, that may not prevent their injury or mortality as a consequence of vessel strike. Here we report a case of a likely collision between a Common Dolphin Delphinus sp. and a recreational vessel in the Hauraki Gulf, New Zealand. Injuries sustained by the immature male dolphin were fatal. Recovery and subsequent post-mortem of the carcass revealed a transection of the spinal cord, with the vertebral column sustaining fractures between L17 and Cd7 and between Cd3 and Cd8 of the neural and transverse processes, respectively. Cd4 likely received the brunt of the impact given the vertebral body and epiphyses were also fractured. Paralysis of the lower truck and associated extensive internal injuries resulted in a live stranding and subsequent mortality. Injuries sustained were consistent of those of blunt force trauma, a consequence of an impact caused by a collision with a small watercraft, most likely a jet-ski. This incident reinforces the need for continued public education concerning safe water practices around marine mammals, which are protected under the New Zealand Marine Mammals Protection Act 1978 and Marine Mammals Protection Regulations 1992.

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Tourist Disturbance On New Zealand Fur Seals (Arctophalus Forsteri)

Australian Mammalogy ◽

10.1071/am02085 ◽

2002 ◽

Vol 24 (1) ◽

pp. 85 ◽

Cited By ~ 24

Author(s):

LJ Boren ◽

NJ Gemmell ◽

KJ Barton

Keyword(s):

New Zealand ◽

Marine Mammals ◽

Effective Management ◽

Negative Effects ◽

Management Guidelines ◽

Tourist Attractions ◽

Fur Seals ◽

Fur Seal ◽

Current Minimum ◽

The Impact

Marine mammals are significant tourist attractions around New Zealand, however, the impact of eco-tourism on these species is poorly documented. Effective management to mitigate any negative effects requires an understanding of target species? reactions to tourist activities. We have studied the effects of tourist activities on New Zealand fur seals (Arctocephalus forsteri) using a novel combination of observations and controlled approaches. Three study areas were selected reflecting a range of visitor density, type of tourism, and the anticipated sensitivity of fur seals to disturbance. Behaviour was observed using instantaneous scan sampling and attributes of tourist approaches were tested experimentally by controlled approaches. Approaches were made on land, by kayak, and motorboat. Fur seal responses and the distance at which the seal responded were recorded. Our results indicate that A. forsteri behaviour was being modified by tourist activities. Habituation was occurring at study areas with high levels of tourist activity. Approachers following current minimum approach distances still caused some animals to modify their behaviour and new minimum approach distances are recommended based on controlled approaches to seals at all study areas. Our work demonstrated that controlled approaches can be a useful tool to develop effective management guidelines to lessen impacts from eco-tourism activities.

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