Science corner: latest fish & fisheries research

[John F]

Not really fisheries, but...


Plastic Pollution in the World’s Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea

* Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions.

* An estimate of the total number of plastic particles and their weight floating in the world’s oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, costal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N5680) and visual survey transects of large plastic debris (N5891) is reported.

* Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, a minimum of 5.25 trillion particles weighing 268,940 tons is estimated.

* When comparing between four size classes, two microplastic <4.75 mm and meso- and macroplastic > 4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove <4.75 mm plastic particles from the ocean surface.

PDF available

Reference:
Eriksen, M., L. C. M. Lebreton, H. S. Carson, M. Thiel, C. J. Moore, J. C. Borerro, F. Galgani, P. G. Ryan & J. Reisser (2014). Plastic pollution in the world’s oceans: More than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLoS ONE, 9 (12): e111913.

[John F]

Post-release mortality in istiophorid billfish

* Meta-analysis (inverse-variance, random-effects model) involving 46 studies was used to estimate the effect size of post-release mortality (Fr) in six istiophorid billfish species (black marlin Istiompax indica, blue marlin Makaira nigricans, longbill spearfish Tetrapturus pfluegeri, sailfish Istiophorus platypterus, striped marlin Kajikia audax, and white marlin K. albida) following release from recreational, longline, and harpoon fishing gears.

* The studies involved 400 reporting pop-up satellite archival tags and 64 reporting acoustic (ultrasonic) tags.

* Despite fish being captured, tagged, and released under widely disparate conditions, locations, and gear types; Fr was homogeneous between species.

* Variability in Fr was principally due to random sampling error within studies with no evident patterns.

* Fifteen studies (33% of tags) indicated no mortality and the overall summary effect size for Fr was 13.5% (95% CI: 10.3 – 17.6%).

* Since the random-effects model decomposed to a fixed-effect model when the between-studies variance T2 = 0.00; results were confirmed using exact nonparametric inferential tests and sensitivity analyses.

* The results support earlier findings in the Atlantic and substantiate the majority of istiophorid billfish survive when released from recreational and longline fishing gear, clearly implying catch-and-release as a viable management option that permits fishing activity while protecting parental biomass and the fishery.

PDF available.

Reference:
Musyl, M. K., C. D. Moyes, R. W. Brill, B. L. Mourato, A. West, L. M. McNaughton, W.-C. Chiang & C.-L. Sun (in press). Post-release mortality in istiophorid billfish. Canadian Journal of Fisheries and Aquatic Sciences, 10.1139/cjfas-2014-0323

[John F]

This is a really important piece of research. It basically says that only 13.5% of the billfish released dies... irrespective of species, conditions, bleeding, etc, etc.

So, the argument "the fish was badly hooked (or was bleeding badly) and would not survive, so we landed it!", holds even less water!!!!!

[John F]

Aspects of the biology and life history of largespot pompano, Trachinotus botla, in South Africa


* Trachinotus botla is an important recreational surf   zone-dependent fish species distributed in the Indo-west Pacific from   South Africa to Australia.

* In South Africa it is restricted to the   northern KwaZulu-Natal coast.

* Biological investigations revealed that it   is a fast growing species that attains a maximum age of ~7 years.

* Males   and females sexually matured in their third year.

* It has a protracted   summer spawning season with evidence of serial spawning behaviour.

* T. botla   is an opportunistic predator with a generalist diet, with fish feeding   on a wide variety of prey items particularly those that are temporally   ‘superabundant’.

* Small fish fed predominantly on copepods and   terrestrial insects, whereas larger fish consumed bivalves and crabs.   

* Teleosts, primarily engraulids, were important components to the diet of   fish of all sizes.

* An ontogenetic dietary shift was observed just after   sexual maturity (~300-mm fork length) that is possibly linked to a   change in habitat preference with larger fish foraging on deeper reefs.

PDF available.

Reference:
  Parker, D.                                                                                                   & A. J.   Booth (2015). Aspects of the biology and life history of largespot pompano, Trachinotus botla, in South Africa. Marine and Freshwater Research,   66(3): 247-255.

[John F]

Movement patterns of surf-zone fish species in a subtropical marine protected area on the east coast of South Africa

* A long-term mark-recapture study was used to assess the movement patterns of surf-zone fishes in the St Lucia Marine Reserve, a marine protected area within the iSimangaliso Wetland Park, a World Heritage Site on the east coast of South Africa.

* Between 2001 and 2013, 6 613 fish from 71 species, caught by hook and line, were tagged at four sites within and adjacent to a no-take marine sanctuary area.

* A total of 1 004 (15.2%) recaptures were made from 17 species.

* The majority (82.4%) of these species displayed station-keeping behaviour, whereas only three were classified as wider-ranging species, and no species with discernible migratory behaviour was observed.

* Findings for five species with the highest recapture rates, namely Pomadasys furcatus, Epinephelus andersoni, E. marginatus, Dinoperca petersi and Lutjanus rivulatus, are presented in greater detail.

* Recapture rates ranged from 7% to 50% and time at liberty from 0 to 3 163 days.

* Individuals of all five species displayed station-keeping behaviour, with the 95th percentile of intra-study-site movements varying between 200 and 1 025 m (linear distance).

* However, four of the five species also displayed some ranging behaviour and made exploratory excursions ranging from 3.5 to 125 km, in both northerly and southerly directions.

* The dominance of stationkeeping behaviour suggests that the St Lucia Marine Reserve sanctuary zone provides an important refuge for these species, with some export to adjacent areas.


pdf available

Reference:

Mann, B. Q., P. D Cowley & S. T. Fennessy (2015). Movement patterns of surf-zone fish species in a subtropical marine protected area on the east coast of South Africa. African Journal of Marine Science, 37: 99-114.

[John F]

Scientists discover first warm-bodied fish!!!!!

http://news.sciencemag.org/biology/2015/05/scientists-discover-first-warm-bodied-fish?utm_source=facebook&utm_medium=social&utm_campaign=facebook

[FishStyx]

Fascinating!

[FishStyx]

Just spotted an article on Biznews about the Opah and looks like it's taken the fancy of some chefs... "This discovery is surprising since the opah is large and conspicuous; indeed, it’s already a favourite in fish markets and restaurants. Wegner and his colleagues deserve great credit for recognising and describing in detail the specialised gill heat exchangers that have been hidden right under the noses of fishermen and chefs for centuries."

I hope it doesn't become over exploited because of it's uniqueness.

http://www.biznews.com/light/2015/05/15/the-moonfish-first-warm-blooded-fish-and-a-favourite-in-markets-restaurants/

[icstuff]

Less fish on the hooks does not necessarily mean less fish in the sea

To avoid overfishing and aid in sustainable exploitation, the status of the fish stocks has to be monitored regularly. In many cases stock assessment is based on fishery-dependent data generated from fish markets or creel surveys. The assumption is: the lower the catches in a certain unit of time, the smaller the stock of fish should be. Biologists have now shown that some fish species show enhanced gear-avoidance behavior in regions with high angling intensity compared to fish exposed to low levels of exploitation near marine protected areas.

Reference:
Forschungsverbund Berlin e.V. (FVB). "Clever fish around the coast of Mallorca Island avoid fishing lines." ScienceDaily. ScienceDaily, 20 May 2015. <www.sciencedaily.com/releases/2015/05/150520083129.htm>.

Article:
http://www.sciencedaily.com/releases/2015/05/150520083129.htm

[Seventenths]

Wow... that Garrick was laughing at my lure the other day... now I know why hook avoidance and prolonged inspection must have revealed it was there to fool him... Very interesting. Thanks Icstuff...

[FishStyx]

Scientists discover first warm-bodied fish!!!!!

http://news.sciencemag.org/biology/2015/05/scientists-discover-first-warm-bodied-fish?utm_source=facebook&utm_medium=social&utm_campaign=facebook

Big Fishes of the World: Lucky anglers catch THREE extremely rare OPAH fish in one day

[John F]

Fish are smarter than we may think!!!!

By revealing that fish cooperate, cheat and punish, Redouan Bshary has challenged ideas about brain evolution

http://www.nature.com/news/animal-behaviour-inside-the-cunning-caring-and-greedy-minds-of-fish-1.17614?WT.ec_id=NATURE-20150528

[FishStyx]

Very interesting... I've always felt that animals in general have a whole lot more intelligence that we give them credit.


The two are such "bad boys" 

[colin]

  very interesting, I have heard many times that fish in heavily fished areas are much more wary of bait and visible line than those in isolated less frequented areas. Have also been told that a carp has roughly the intelligence of a domestic fowl and similar responses to frights and food , eg: they will eat slowly when alone, but will go into a frenzy when competition arrives.

[John F]

Parrotfish identified as major producers of island-building sediment in the Maldives

* Reef islands are unique landforms composed entirely of sediment produced on the surrounding coral reefs.

* Despite the fundamental importance of these ecological-sedimentary links for island development and future maintenance, reef island sediment production regimes remain poorly quantified.

* Using census and sedimentary data from Vakkaru island (Maldives), a sand-dominated atoll interior island, the major sediment-generating habitats, the abundance of sediment producers in these habitats, and the rates and size fractions of sediment generated by different taxa was quantified.

* The estimated annual sediment production is 685,000 kg (or 370 m3), ~75% of which is produced on the narrow outer reef flat, despite composing only 21% of the total platform area.

* Approximately 65% of the platform acts solely as a sediment sink.

* Census data identify parrotfish as the major sediment producers, generating >85% of the 5.7 kg/m2 of new sand-grade sediment produced on the outer reef flat each year.

* Halimeda (macroalgae) produce a further 10%, most as gravelgrade material.

* Comparisons between production estimates and sedimentary data indicate that reef ecology and island sedimentology are tightly linked; reef flat and lagoon sediments are dominated by coral and Halimeda, although fine- to medium-grained coral sand is the dominant (~59%) island constituent.

* The generation of sediment suitable for maintaining this reef island is thus critically dependent on a narrow zone of high-productivity reef, but most especially on the maintenance of healthy parrotfish populations that can convert reef
framework to sand-grade sediment.


PDF available.

Reference:

Perry, C. T., P. S. Kench, M. J. O’Leary, K. M. Morgan & F. Januchowski-Hartley (2015). Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives. Geology, 43: 503-506.

[John F]

Here's a nice site with daily news on marine biology and science in general.

http://www.sciencedaily.com/news/plants_animals/marine_biology/

[FishStyx]

Red Map... an interesting app that helps keep track of how species are moving in response to climate change. It gives ordinary Oz citizens a chance to be part of science. Hopefully, it will extend around the globe and give us a better picture of how climate change is manifesting.


http://blogs.discovermagazine.com/citizen-science-salon/2015/06/19/science-behind-the-camera-snapping-pictures-for-climate-research/#.VYaah_mqqkr


And a short vid:


https://www.facebook.com/UniversityofTasmania/videos/10155634579945008/

[John F]

Population structure of black musselcracker Cymatoceps nasutus: evidence for multiple populations in South African coastal waters

* Genetic studies on South African marine fishes have shown that many species exist as single, well-mixed stocks
throughout their core distribution;

* The black musselcracker or poenskop Cymatoceps nasutus is a slow-growing, late-maturing and long-lived sparid (Perciformes: Sparidae) that is endemic to South African coastal waters.

* Conventional tagging studies suggest that it is resident, with limited connectivity between different regions
along the coast;

Mitochondrial and nuclear DNA were used to investigate the genetic structure of C. nasutus along the South African coastline and showed evidence of at least two populations;

* Samples collected from the Tsitsikamma Marine Protected Area on the South Coast to KwaZulu-Natal on the East Coast showed no significant population structure over much of the distribution;

* Gene flow for C. nasutus within this region is not limited by geographic distance and appears to be unaffected by various oceanographic barriers and biogeographical boundaries;

* Samples from the Western Cape to the west of Tsitsikamma, however, showed moderate to substantial differentiation for both markers, which may be influenced by a temperature barrier – a coldwater ridge – along the South Coast;

* These data provide the first genetic assessment of this South African sparid, and suggest that a two-stock management strategy would be appropriate for the species.


PDF available.

Reference:
Murray, T. S., G. Gouws, M. Mwale, B. Q. Mann & P. D. Cowley (2014). Unravelling population structure of black musselcracker Cymatoceps nasutus: evidence for multiple populations in South African coastal waters. African Journal of Marine Science, 36: 493-503.

[John F]

Controlling outbreaks of the coral-eating crown-of-thorns starfish using a single injection of common household vinegar

* Outbreaks of the destructive coral-eating crown-of-thorns starfish, Acanthaster planci,   present a considerable threat to coral reefs worldwide, and mitigating   their impact has proven challenging.

* The most effective methods to   control A. planci require injecting   individual starfish with lethal chemicals.

* While some of these are   highly effective, their administration often requires permits, training   and access to specialised equipment. We aimed to identify a widely   available and highly efficient alternative.

* It was discovered that common   household vinegar is lethal to A. planci   individuals when injected at the base of one their arms.

* A single   injection of 25 ml vinegar induced functional mortality in <24 h and   100 % mortality in <48 h.

* These results demonstrate that vinegar is   an effective alternative to currently used chemicals.

* Vinegar is a   viable alternative in the toolkit of methods that can control and   eradicate local outbreaks of COTS on coral reefs.


PDF available.

Reference:
Boström-Einarsson, L. & J. Rivera-Posada (2015). Controlling outbreaks of the coral-eating crown-of-thorns starfish using a single injection of common household vinegar. Journal: Coral Reefs. DOI 10.1007/s00338-015-1351-6.

[SAfish]

Thanks for sharing, Marcos. It is very interesting and I am sure the vinegar is a much more 'greener' and cheaper alternative.