Size-selective predation by river otter (Lontra canadensis) improves refuge properties of shallow coastal marine nursery habitats

Young fish often avoid deep water to reduce predation risk from larger fish. Less clear are explanations for the avoidance of shallows by large piscivorous fish; however, one hypothesis suggests that this distribution reduces contact with depth-limited semi-aquatic mammal and bird piscivores. We determined prey size selection of the river otter ( Lontra canadensis (Schreber, 1777)) to test the hypothesis that larger fish are at elevated risk in shallow coastal waters in Newman Sound, Newfoundland, during June–November 2001 and May 2002. We compared otter diet (scat analysis) and prey availability (seine sampling) to test this hypothesis. Five fish taxa (Atlantic cod ( Gadus morhua L., 1758), Greenland cod ( Gadus ogac Richardson, 1836), shorthorn sculpin ( Myoxocephalus scorpius (L., 1758)), cunner ( Tautogolabrus adspersus (Walbaum, 1792)), and winter flounder ( Pseudopleuronectes americanus (Walbaum, 1792))) dominated the shallow-water fish community and were sufficiently abundant in otter scats to examine feeding preferences. Larger, piscivorous fish were selected by otters, suggesting that they were at greater risk of predation than smaller fish, consistent with our hypothesis that depth-limited, diurnally active predators restrict large fish from hunting in shallow water during daytime. We suggest that depth-limited air-breathing predators may reduce the presence of such predatory fish in shallow-water juvenile fish nursery habitats.

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Predation on small juvenile fishes in shallow estuarine nursery areas: Reply to Baker & Sheaves (2021)

Marine Ecology Progress Series ◽

10.3354/meps13678 ◽

2021 ◽

Vol 662 ◽

pp. 209-214

Author(s):

A Whitfield

Keyword(s):

South Africa ◽

Juvenile Fish ◽

Fish Predation ◽

Estuarine Waters ◽

Fish Nursery ◽

Piscivorous Fish ◽

Small Juvenile ◽

Nursery Habitats ◽

High Predation ◽

Counter Argument

The key criticism by Baker & Sheaves (2021; Mar Ecol Prog Ser 662:205-208) of the Whitfield (2020; Mar Ecol Prog Ser 649:219-234) estuarine littoral predation paradigm review is that shallow water fish nursery habitats contain abundant predator assemblages which may create high predation pressure on the juvenile fish cohorts that occupy these areas. The primary arguments supporting Baker & Sheaves’ criticism arise from a series of papers published by them on piscivorous fish predation in certain tropical Australian estuaries. The counter-argument that shallow littoral areas in estuaries do indeed provide small juvenile fishes with refuge from small and large piscivorous fishes is provided by published papers from 4 different estuary types in South Africa, covering both subtropical and warm-temperate systems. Based on the overall published information, the argument for shallow (<1 m depth) estuarine waters providing major protection for newly settled juveniles appears to be weak in northern Australia but strong in South Africa. The global situation, as outlined in this response, is more supportive of low piscivorous predation in shallow nursery habitats, but further targeted research is needed before we can confirm that littoral estuarine waters are indeed a universal keystone attribute in this regard.

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Littoral habitats as major nursery areas for fish species in estuaries: a reinforcement of the reduced predation paradigm

Marine Ecology Progress Series ◽

10.3354/meps13459 ◽

2020 ◽

Vol 649 ◽

pp. 219-234 ◽

Cited By ~ 1

Author(s):

AK Whitfield

Keyword(s):

Fish Species ◽

Juvenile Fish ◽

High Energy ◽

Global Scale ◽

Nursery Areas ◽

Fish Nursery ◽

Piscivorous Fish ◽

Dominant Component ◽

Littoral Habitats

For many decades, the role of estuaries as important nursery areas for fishes was accepted as fact by scientists and environmental managers. At the turn of the 21st century, a question mark was raised in relation to the reduced predation component of the nursery function, with some scientists contending that both large and small piscivorous fish species had access to the estuarine habitats that juvenile fishes in estuaries occupied. If true on a global scale, the nursery designation for these habitats would be compromised and the long-held paradigm that estuaries are important nursery areas for fishes would need to be revised. In this review, I examine the nature of fish nursery areas in estuarine littoral habitats from a mainly predation perspective and, based on a variety of ichthyofaunal and avifaunal studies, come to the conclusion that apart from a few selected estuarine systems, there is limited predation on juvenile fishes in these particular areas. This, coupled with the abundant suitable food resources for juvenile fish from different trophic categories, shelter from high-energy marine wave action and biological connectivity between a variety of submerged and emergent macrophyte communities, renders shallow estuarine littoral areas ideal nursery areas for the juveniles of mostly euryhaline marine fish species, the dominant component of estuarine ichthyofaunas globally. In addition, there are strong indications from the fossil record that these littoral estuarine nursery areas have been functioning since the Devonian, more than 350 million years ago.

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Modeling Behavior by Coastal River Otter (Lontra Canadensis) in Response to Prey Availability in Prince William Sound, Alaska: A Spatially-Explicit Individual-Based Approach

PLoS ONE ◽

10.1371/journal.pone.0126208 ◽

2015 ◽

Vol 10 (6) ◽

pp. e0126208 ◽

Cited By ~ 5

Author(s):

Shannon E. Albeke ◽

Nathan P. Nibbelink ◽

Merav Ben-David

Keyword(s):

Prey Availability ◽

Lontra Canadensis ◽

Spatially Explicit ◽

Prince William Sound ◽

River Otter ◽

Modeling Behavior ◽

Coastal River

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Development of Atlantic cod (Gadus morhua) exposed to produced water during early life stages: Effects on embryos, larvae, and juvenile fish

Marine Environmental Research ◽

10.1016/j.marenvres.2010.08.002 ◽

2010 ◽

Vol 70 (5) ◽

pp. 383-394 ◽

Cited By ~ 50

Author(s):

Sonnich Meier ◽

H. Craig Morton ◽

Gunnar Nyhammer ◽

Bjørn Einar Grøsvik ◽

Valeri Makhotin ◽

...

Keyword(s):

Early Life ◽

Gadus Morhua ◽

Produced Water ◽

Atlantic Cod ◽

Juvenile Fish ◽

Life Stages ◽

Early Life Stages

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A River Otter's, Lontra canadensis, Capture of a Double-crested Cormorant, Phalacrocorax auritus, in British Columbia's Gulf Island Waters

The Canadian Field-Naturalist ◽

10.22621/cfn.v121i3.483 ◽

2007 ◽

Vol 121 (3) ◽

pp. 325

Author(s):

Michael H. H. Price ◽

Clare E. Aries

Keyword(s):

Lontra Canadensis ◽

Phalacrocorax Auritus ◽

River Otter ◽

Freshwater Lakes ◽

Marine Bird ◽

River Otters

Direct and apparent predation events by River Otters (Lontra canadensis) on birds have been recorded on marine islands and freshwater lakes. We add to this the first known observation of a River Otter capturing a marine bird on the ocean.

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Casitas: a location-dependent ecological trap for juvenile Caribbean spiny lobsters, Panulirus argus

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv041 ◽

2015 ◽

Vol 72 (suppl_1) ◽

pp. i177-i184 ◽

Cited By ~ 7

Author(s):

Benjamin C. Gutzler ◽

Mark J. Butler ◽

Donald C. Behringer

Keyword(s):

Florida Keys ◽

Nutritional Condition ◽

Ecological Trap ◽

Habitat Modification ◽

Panulirus Argus ◽

Risk Of Predation ◽

Spiny Lobsters ◽

Nursery Habitats ◽

Animal Size ◽

Fisheries Enhancement

Abstract Casitas are artificial shelters used by fishers to aggregate Caribbean spiny lobsters (Panulirus argus) for ease of capture. However, casitas may function as an ecological trap for juvenile lobsters if they are attracted to casitas and their growth or mortality is poorer compared with natural shelters. We hypothesized that juvenile lobsters may be at particular risk if attracted to casitas because they are less able than larger individuals to defend themselves, and do not forage far from shelter. We compared the nutritional condition, relative mortality, and activity of lobsters of various sizes in casitas and natural shelters in adult and juvenile lobster-dominated habitats in the Florida Keys (United States). We found that the ecological effects of casitas are complex and location-dependent. Lobsters collected from casitas and natural shelters did not differ in nutritional condition. However, juvenile lobsters in casitas experienced higher rates of mortality than did individuals in natural shelters; the mortality of large lobsters did not differ between casitas and natural shelters. Thus, casitas only function as ecological traps when deployed in nursery habitats where juvenile lobsters are lured by conspecifics to casitas where their risk of predation is higher. These results highlight the importance of accounting for animal size and location-dependent effects when considering the consequences of habitat modification for fisheries enhancement.

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River Otter (Lontra canadensis) Food Habits in a Washington Coast Watershed: Implications for a Threatened Species

Northwestern Naturalist ◽

10.1898/1051-1733-97.1.36 ◽

2016 ◽

Vol 97 (1) ◽

pp. 36-47 ◽

Cited By ~ 2

Author(s):

Jonathan J Scordino ◽

Patrick J Gearin ◽

Susan D Riemer ◽

Eric M Iwamoto

Keyword(s):

Threatened Species ◽

Food Habits ◽

Lontra Canadensis ◽

River Otter

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River Otter Distribution and Food Habits in Grand Teton National Park as Part of an Ongoing Project in the GYE

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.2015.4099 ◽

2015 ◽

Vol 38 ◽

pp. 75-78

Author(s):

Kelly Pearce ◽

Tom Serfass

Keyword(s):

National Park ◽

Activity Patterns ◽

Public Support ◽

Primary Objective ◽

Camera Traps ◽

Lontra Canadensis ◽

Flagship Species ◽

River Otter ◽

Grand Teton National Park ◽

River Otters

Grand Teton National Park is part of the known range of the North American river otter, however not much is known about this semi-aquatic mammal within the park. The results presented here are part of a larger project to investigate the potential of the river otter (Lontra canadensis) to serve as an aquatic flagship (species that engender public support and action) for the Greater Yellowstone Ecosystem. River otters, known for their charismatic behavior have the potential to serve as an aquatic flagship species to promote conservation of aquatic ecosystems. The primary objective of this portion of the study was to identify river otter latrines on portions of the Snake River, between Flagg Ranch and Jackson Lake, and between Jackson Lake Dam and Pacific Creek, collect river otter scats to determine diet of the river otter, and employ remote cameras to determine activity patterns of the river otters. Between 20 June and 1 July 2015, 26 river otter latrines were identified during shoreline surveys, 186 river otter scats were collected, and cameras were deployed at 6 latrines between 7 July and 24 August 2015. River otter scats have been cleaned and prepared for analysis, but have not all been processed to date. Camera traps recorded 222 images, of which 7% (n = 14) were of carnivores, 70% (n = 155) were of non-carnivore mammals, and 9% (n = 22) were of birds. River otters were detected at 1 of the 6 latrines, a total of 5 independent times during the study.

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Fish nursery value of algae habitats in temperate coastal reefs

PeerJ ◽

10.7717/peerj.6797 ◽

2019 ◽

Vol 7 ◽

pp. e6797 ◽

Cited By ~ 1

Author(s):

Hilmar Hinz ◽

Olga Reñones ◽

Adam Gouraguine ◽

Andrew F. Johnson ◽

Joan Moranta

Keyword(s):

Juvenile Fish ◽

Strong Association ◽

Late Summer ◽

Early Spring ◽

Rocky Reef ◽

Term Survival ◽

Fish Nursery ◽

Prey Biomass ◽

Reduced Height ◽

Time Of Year

The nursery function of coastal habitats is one of the most frequently mentioned and recognized ecosystem services in the valuation of coastal ecosystems. Despite its importance our understanding of the precise habitat parameters and mechanisms that make a habitat important as a nursery area is still limited for many species. The study aimed to establish the importance of different algae morphotypes in providing shelter and food for juvenile coastal fish during the main settlement peaks, in early spring and late summer, in littoral rocky reef systems in the Northwestern Mediterranean. The results of our study showed strong seasonal differences in algae cover, composition and height between the two sampling periods. Overall, during spring the algae were well developed, while in late summer, both density and height, of most algae decreased considerably. Equally, prey biomass, in form of suitable sized invertebrate fauna associated to the algae, decreased. Accordingly, the shelter and food for the fish settling in this habitat during late summer were less abundant, indicating a mismatch between the observed presence of juvenile fish and optimal habitat conditions. Differences in prey densities were detected between algae morphotypes, with structurally more complex algae, such as Cystoseira spp. and Halopteris spp. consistently containing more prey, independent of season, compared to simpler structured morphotypes such as Dictoytales. The study furthermore related juvenile fish density to habitats dominated by different algae morphotypes. Out of the three-study species (Diplodus vulgaris, Symphodus ocellatus, Coris julis) only S. ocellatus showed a significant association with an algae habitat. S. ocellatus related positively to habitats dominated by Dictoytales which provided the highest cover during late summer but had the lowest prey densities. A strong association of this species with Cystoseira, as reported by other studies, could not be confirmed. Cystoseira was abundant within the study area but in a state of dieback, showing loss and reduced height of foliage, typical for the time of year within the study area. It is therefore likely that algae-fish associations are context-dependent and that several algae species may fulfil similar functions. We also discovered that prey biomass did not appear to have an important effect on juvenile abundances. Nevertheless, the availability of prey may influence juvenile fish condition, growth performance and ultimately long-term survival. We therefore suggest that future studies on habitat quality should also include, besides abundance, indicators related to the condition and growth of juveniles.

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