Bottle nosed dolphins living along the coast of Florida are getting used to supplement their diet by snatching bait from fishing lines or circle recreational anglers practising catch-and-release. Some dolphins have even made a habit out of routinely approaching humans to beg for food.

Scientists at the National Marine Fisheries Service have now been able to show that this behaviour is spread down through generations of dolphins.

“We are able to document lineage, from grandmother to mother to calf, all following fishing boats and taking thrown-back fish,” says Jessica Powell, a National Marine Fisheries Service biologist.

Dolphins begging for food might be an endearing sight, but approaching humans in this fashion means taking a great risk. In 2006, three dead Sarasota Bay dolphins turned out to have fishing lures stuck inside them.

“Whenever animals become reliant on humans for food, it puts them at jeopardy,” says Dr. Randy Wells, director of dolphin research at Sarasota’s Mote Marine Laboratory. “If they are coming to boats or piers to get fish, they are swimming through a maze of lines, hooks and lures and those lines are designed to be invisible under water.”

Some dolphins do however seem to have figure out how to stay clear of harms way. A bottlenose dolphin nicknamed “Beggar” has been soliciting free meals in a narrow stretch of Intracoastal Waterway near Nokomis Beach since he was a juvenile 20 years ago. Despite routinely swimming just inches from boat propellers, the skin of Beggar’s 8 feet long body is free of major scars. Hopefully, the same is true for the inside of his 400 pound body.

As if the menace of razor sharp propeller blades, invisible fishing lines and jagged double hooks weren’t enough, bottlenose dolphins also stand the risk of encountering anglers who may not appreciate having their bait or catch snatched away by a hungry cetacean. A commercial fisherman out of Panama City, Florida has been sentenced to two years in prison after throwing pipe bombs at dolphins trying to steal his catch. Off Panama City, tour operators have been feeding dolphins for years to assure their presence at the popular “swim-with-the-dolphins” tours.

Feeding the Florida dolphins is illegal under both state and federal law, with federal law banning wild dolphin feeding in the early 1990s. Feeding wild dolphins can also be dangerous and the abovementioned “Beggar” dolphin has for instance sent dozens of overfriendly patters to the hospital for stitches and antibiotics.

Hand-feeding aside, a severe red tide in 2005 seems to have made the habit of interacting with humans for food much more widespread than before among the Florida dolphins. The red tide wiped out 75-95 percent of the dolphin’s usual prey fish and the hungry dolphins eventually realised that they could fill their bellies by picking bait fish off fishing lines.

“We suspect that the dolphins were
hungry,” Wells explains. “Their main prey
base was gone. Seeing a fresh pin fish
dangling from a line might look pretty
good to them. And once they learned
that anglers are a source of food, they
don’t forget that very quickly.”

The European River Otter (Lutra lutra) which was once almost eradicated from British waters is beginning to make a come-back thanks to improved environmental care and the reintroduction of captive-bred specimens.

Now, anglers and fishing clubs are calling for more research, governmentally funded fences, and – in some cases – even the right to cull otters. Some fishing clubs have already closed down after having their stocks devoured by otters, while others have been forced to lower their fees since they have less fish to offer than before. Clubs are also spending thousands of pounds on restocking their ponds.

Until the 1970s, otters were hunted in the kingdom using special otter hounds, and the population also suffered greatly from the consequences of habitat destruction and pollution. The use of pesticides proved especially fatal and in the 1970s the population was almost completely gone. Thanks to pollution control, habitat restoration, and a ban on otter hunting, the UK has however once again became a favourable country for this aquatic predator and the reintroduction of captive-bred have proven highly successful. Otters are now living even in urban rivers.

Dr Tony Mitchell-Jones, a mammal specialist from Natural England, said that otters had been released into the wild at the rate of more than seven a year between 1983 and 1999, but that no captive-bred otters had been released since then.

When the last large-scale survey was carried out in 2003, the European river otter was found in more than five times as many areas as in 1979.

On June 9, a meeting will take place in Hemel Hempstead were representatives of the Angling Trust, the Environment Agency, Natural England, and the Countryside Council for Wales will discuss the issue of otters competing with anglers for fish. The Angling Trust has announced that they will exact government support for special otter fences in an effort to quieten calls for a cull.

Mark Lloyd, the chief executive, said: “What we need is public funding for fencing because fisheries are important economic units that provide people with their livelihoods. What has to be stressed is that anglers are not anti-otter. If I see one when I’m fishing on a river it makes my day.”

Nick Pottle, secretary of the Lakeside angling club, near Lowestoft, said: “Our lake is now all but empty of fish, we have two families of otters that have cleared the fish out. The Environment Agency say we must put up a fence to stop the otters at our expense as we would not qualify for a grant. That is the end of our club.”

The Angling Times, a journal for sport fishers, are calling for more research into otter predation. Richard Lee, its editor, said: “The slaughter of these animals has been driven underground. It is already going on. If you watch £20,000 worth of stock disappear in just a few days – what are the owners going to do? We are desperate for research so the issue is fully understood. We don’t want random culling. But we want to stop fisheries’ owners taking the law into their own hands. We need some proper research with all the options on the table.”

One of the reasons behind the belligerent situation may be another man-made environmental problem: the disappearance of the eels. During recent years, the number of eels has fallen dramatically in British waters. Eels are the otter’s staple diet and as long as there are plenty of eels the risk of otters attacking trout, salmon, pike, and similar species is low. However, as the eel population wanes the otters are forced to look elsewhere for food – causing confrontations between them and fishermen who do not like to see vast amounts of highly prized fish species ending up in the belly of an otter.

Many anglers refuse to publicly discuss otter hunting, fearing that public opinion will turn against them if they openly call for culling. On of few anglers openly arguing in favour of culling is Ian Chillcott, one of the country’s leading coarse anglers and a fishing writer. “Fisheries are being absolutely destroyed by these cuddly, little murdering blighters”, Chillcott said. “Livelihoods are being ruined but everyone is afraid to use the word ‘culling’. No one wants widespread mass slaughter, but there is a need for very targeted culling. It has to be done in a controlled way and not indiscriminate. No one wants to get rid of them, just for them to be better managed.”

Mitchell-Jones does not think that licensed killing of otters will take place anytime soon.

“Things are looking much better for the otter but it is not yet back everywhere it should be. Control of otter populations is likely to be discussed at the meeting tomorrow. I’m not going to prejudge the situation but there is a presumption against the licensing of killing of protected species unless there are extremely good reasons for doing so. For culling, you would have to show that the control would contribute to the solution of a problem.”

In the mean time, there are indications of some landowners and fishermen taking the law into their own hands. Under the Wildlife and Countryside Act it is an offence to kill an otter, punishable by a £5,000 fine or six months in prison. Otters can only be hunted with a special licence and not a single one of these licenses has been issued. Despite this, some anglers have told reporters of otter hunting taking place in the British countryside.

Scientists tagging sharks off the Irish coast have tagged a surprisingly high number of Basking sharks this year: 50 specimens in just three days.

“I would normally expect to be lucky if we tagged 50 in a whole year,” said Dr Simon Berrow of the Irish Whale and Dolphin Group.

Basking SharkA record

Together with National Parks and Wildlife Service conservation ranger Emmett Johnston, Dr Berrow set out earlier this week to tag sharks off Donegal, as part of a project funded by the Heritage Council.

“In two hours last Monday we tagged 23 sharks, and we found 19 the following day – four of which had been tagged the day before,” Dr Berrow said. By the third day, they had tagged their 50^th basking shark.

Basking sharks were once a significant source of income for Irish whalers and the coastal towns of Galway and Waterford did for instance have street lights lit with basking shark oil as early as the 18^th century.

The importance of Basking sharks in Irish culture is evident in the number of names and monikers give to these peculiar creatures. In Irish, this “monster with sails” is known under the names Liabhán chor gréine (Great fish of the sun), Liop an dá (unwieldy beast with two finns) and Liabhán mór (great leviathan) – just to mention a few. The epithets “Fish of the sun” and “Sunfish” both pertains to its fondness of swimming just under the surface.

In the mid-1970s the Irish stopped their whaling, but the problems weren’t over for these sharks since they frequently ended up as by-catch in drift nets; a fishing method now outlawed in Irish waters. In addition to this, Norwegian whalers continued to hunt for shark off the Irish coast until 1986.

The Basking shark (Cetorhinus maximus) is listed as Vulnerable on the IUCN Red List of Threatened Species, and is a protected species in Great Britain but not in Ireland. However, the European Union has just placed a moratorium on fishing for Basking sharks in these waters.

If you spot a Basking shark in Irish waters, the Irish Whale and Dolphin Group would very much like to know any details about the sighting. You can find more information at www.baskingshark.ie.

Want to know more about Basking sharks and where they head when the Northern Seas become too cold for comfort? Check out our earlier blog post on Sharks of the Caribbean.

As reported earlier, an ill-fated eel somehow ended up in the butt of an allegedly constipated Chinese gentleman. Two European fish experts have now taken a closer look at a photograph of the eel in question and given their expert opinion on its identity.

When discussing the fish-in-butt incident with Swedish ichthyologist Dr Sven Kullander, Dr Ralf Britz of London’s Natural History Museum – an expert on the order Synbranchiformes – suggested that this fish might not be an eel at all. Instead, he believes the elongated fish to be a member of the species Monopterus albus, since the tip of its tail is very slender and the gular region somewhat inflated.

Despite not being a true eel, Monopterus albus is commonly known as Asian swamp eel in English. It is a popular food fish in parts of south-east Asia and you can buy it alive in fish markets. All young swamp eels are female but some of the change sex and become male as they age. If a male swamp eel founds itself in an environment with no or very few females, he can change himself back into a female fish again. The change from one sex to the other can take up to a year.

If you ever feel the need to insert a swamp eel into your body, we here at AC Tropical Fish suggest you do it orally.

Swamp Eel Chowder
4 servings

Ingredients
Ruhgly 600 g Monopterus albus
150 g Lean Pork
50 g Dry Black Fungus
5 pieces of Dry Black Mushroom
3 tbsp cooking oil
1 tbsp Shaoxing Wine
1 L Chicken Stock
2 tbsp Shredded Lemon Leaves
1 tbsp Shredded Ginger
1 tbsp Chopped Parsley

Ingredients for seasoning
3 tbsp Water Chestnut Powder
1 tbsp Water
1 tbsp Sesame Oil
1/2 tbsp Dark Soy Sauce
1/2 tbsp Light Soy Sauce
1/2 tbsp Salt
1 tsp pepper

Instructions
1.) Prepare the seasoning by stirring all seasoning ingredients together. Set aside.
2.) Remove the bones from the eel.
3.) Wash the eel meat in hot water and shred it.
4.) Let the black fungus and black mushrooms soak in water until they become soft.
5.) Shred the black fungus and black mushrooms.
6.) Clean the pork and shred it.
7.) Heat up a wok or large frying pan and add the cooking oil.
8.) Add the eel meat to the wok and stir fry.
9.) Add wine and chicken stock and bring to a boil.
10.) Add the shredded fungus, mushrooms, and pork and cook for 5 minutes while stirring.
11.) Add ginger and parsley and cook at low heat for another 5 minutes while stirring.
12.) Add the seasoning, continue to cook and stir for 2 more minutes.
13.) Sprinkle with chopped parsley before serving.

* If you want to see the low resolution picture of the actual specimen extracted at the Kwong Wah Hospital, the paper where it is included has been published in the journal Surgery. “Siu Fai Lo, Sin Hang Wong, Lok Sang Leung, In Chak Law, Andrew Wai Chun Yip, Traumatic rectal perforation by an eel, Surgery, Volume 135, Issue 1, January 2004, Pages 110-111”.

Several types of commonly used fish egg disinfectants increase the risk of swim bladder disorder in fish, a new study from Israel reveals.

In an effort to prevent fungal growth, many fish breeders use various chemicals, such as methylene blue, hydrogen peroxide, acriflavine and chloramine-T to aquariums where eggs are kept. This practise is especially common among breeders who will not let the parents stay with eggs and fry. Many fish species carry out parental care and eggs from such species often depend on one or both parents gently fanning fresh water over them and manually removing any unfertilized eggs from the batch. Without such parental care, the eggs easily succumb to fungi unless the fish breeder adds some type of fungicide to the water.

The new Israeli study, which focused on Angelfish (Pterophyllum scalare), revealed that some of these chemicals may be responsible for a swim bladder disorder in developing fish. In fish suffering from this type of disorder, the swim bladder can not inflate properly and the fry fails to develop into a fully free-swimming adult. Among aquarists, such fish are commonly known as “belly sliders” due to their peculiar way of moving around the fish tank.

Methylene blue

Eggs hatched in the presence of 1, 2 and 5 ppm methylene blue exhibited significant increases in swim bladder non-inflation (11%, 9% and 33%, respectively; none in controls).

Time of exposure to methylene blue was a key factor. Exposure for up to 1 day post-hatch did not affect swim bladder non-inflation, but exposure from 2 days onwards significantly increased swim bladder non-inflation.

Hydrogen peroxide

Hydrogen peroxide at 250 ppm significantly increased swim bladder non-inflation (65% comparing to 27% in the control). Higher concentrations resulted in 100% mortality.

Acriflavin

Exposure to acriflavin at 2.25 ppm, but not 1.25 ppm, significantly increased swim bladder non-inflation (75% and 52% respectively; 20% in controls).

Chloramin-T

Chloramine-T did not significantly affect swim bladder non-inflation.

For more information, see the paper “C. Sanabriaa, A. Diamantb and D. Zilberga (2009) – Effects of commonly used disinfectants and temperature on swim bladder non-inflation in freshwater angelfish, Pterophyllum scalare (Lichtenstein)”. The paper has been published in the journal Aquaculture.

In several species of fish, such as the cichlid species Neolamprologus pulcher, it is common for subordinate females to help an unrelated dominant breeding pair raise their young. The reason behind this seemingly altruistic behaviour, known as alloparental care, has puzzled scientists for many years and one of the most widely spread hypotheses put forward has been the ‘pay-to-stay’ hypothesis. According to the ‘pay-to-stay’ rationale, the subordinate female helps out the dominant pair just to be able to stay in the group. Not being ostracised from the group augments her long-term survival chances, thus increasing the chance for her to live long enough to eventually obtain a breeding position.

Picture by: JJPhoto.dk

A new study carried out by Dik Heg and coauthors does however bring forth a new hypothesis: the substrate rationale. In their study, Heg and his colleges tested the hypothesis that subordinate female cichlids are helping dominant pairs in return for a more immediate direct reproductive benefit. After a series of experiments where the total number of eggs produced over a 30 day period by dominant and subordinate Neolamprologus pulcher females were carefully counted, researchers found that a subordinate female helping out a dominant pair was more likely to produce eggs herself compared to other subordinate females.

According to Heg and coauthors, the most likely reason for the increased reproductive success of “fish nannies” is that the subordinate female gains access to the breeding substrate.

If you wish to read more, see the paper “Heg, D, E Jutzeler, JS Mitchell and IM Hamilton (2009) Helpful female subordinate cichlids are more likely to reproduce”. It has been published in the journal PLoS ONE.

Here at AC Tropical Fish, we believe in the Jude Law-hypothesis. The dominant female will naturally snatch away the most prosperous male, but by posing as a benevolent nanny even a subordinate female can gain access to his home and hope for some of his triumphant DNA to eventually find its way into the genetic make up of her own offspring.

Just like dolphins, sharks can be trained to roll over to be cuddled by humans. In experiments carried out in the United States, several species of shark allowed themselves to be picked up from the water and cuddled by their trainers.

The U.S. trainers used coloured boards and sounds to train their sharks to respond to commands. No one had attempted to train sharks in this way before and the results are truly ground breaking. Shark keepers now hope that the new technique will give sharks a higher quality of life in captivity. When sharks ned to be moved, the normal practise is to chase them around, but a trained shark could instead be thought to just gently swim to a certain spot.

“The US team has shown that many varieties of sharks can quickly learn to respond to a combination of audible and visual signals”, says Carey Duckhouse of UK’s Sea Life Centres.

Keepers at the UK’s Sea Life Centres are planning to use the methods developed in the U.S. to train sharks kept in British facilities. Colour boards and sounds will be used to show each shark when it is his or her turn to receive food. If everything goes according to plan, the fastest learners in the shark tanks will grasp the idea within three months.

When a shark have learned to associate particular colours and sounds with food, the signals will make it approach its keeper who will be holding a “target stick” against which the shark will rub its nose in hope of getting a tasty treat.

”Some species, such as zebra sharks, will even roll over to have their tummies scratched or allow themselves to be lifted from the water without any kind of struggle,” says Dickhouse.

Scientists from the U.S. Geological Survey (USGS) have revealed that largemouth bass injected with oestrogen produces less hepcidin than normally. Hepcidin is an important iron-regulating hormone in fish, amphibians and mammals, and researchers also suspect that hepcidin may act as an antimicrobial peptide. In vertebrate animals, antimicrobial peptides are the body’s first line of defence against unwelcome bacteria and some fungi and viruses, so if there’re right, a lowered amount of these compounds is certainly not good news.

“Our research suggests that estrogen-mimicking compounds may make fish more susceptible to disease by blocking production of hepcidin and other immune-related proteins that help protect fish against disease-causing bacteria,” says lead author Dr. Laura Robertson.

You can find more info in the study “Identification of centrarchid hepcidins and evidence that 17β-estradiol disrupts constitutive expression of hepcidin-1 and inducible expression of hepcidin-2 in largemouth bass (Micropterus salmoides)” by Laura Robertson, Luke Iwanowicz and Jamie Marie Marranca in the latest issue of the journal Fish & Shellfish Immunology. It is the first published study demonstrating control of hepcidin by estrogen in any animal.

In an effort to curb the population of invasive Atlantic sea lampreys (Petromyzon marinus) in the North American Great Lakes, researchers are now testing a “love trap” in northern Michigan.

The traps will be scented with an odour produced by male lampreys during mating and researchers hope that this smelly love potion will lure female lampreys into the traps.

“We are trying to fool them into a fatal love,” said researcher Nick Johnson who will spend the next three years evaluating the effectiveness of the method.

The traps will be placed in ten streams around the Great Lakes, since lampreys swim into streams when it’s time to mate. After spawning, they die.

The Atlantic sea lamprey is native to the Atlantic Ocean but has been able to migrate into the Great Lakes through man-made shipping canals. The first specimens where seen in the region as early as the 1830s. By the 1950s, lampreys had decimated native populations of lake trout and white fish by rasping through their skin and sucking out their blood and bodily fluids. Several other populations of large and commercially important food fish had also been severely damaged by the new resident.

Since 1955, Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service have worked closely on the Great Lakes Fishery Commission to control the Atlantic sea lampreys, using lampricides (substances toxic to lamprey larvae), migration barriers, and sterilization of male lampreys. Hopefully, the new pheromone scented traps will prove an efficient addition to their arsenal.

Criminal gangs are becoming a growing problem in Adelaide, Australia, but unlike most other gangs, these criminals are not fighting over drugs, precious stones or illegal firearms – they’re in it for the fish.

Despite this, the war on gangs launched by Adelaide authorities includes all the usual features; moonlight raids, fencing criminals, confiscation of secret stashes, and officials being seriously assaulted by criminals trying to evade the long arm of the law.

Thanks to a growing black market in restricted fish and shellfish, poachers can earn thousands of dollar per week along the windswept beaches and mangrove forests of South Australia. The 100 km piece of coastline running from Garden Island in the Port River Estuary to Bald Hills Beach, just south of Port Wakefield, seems to be especially popular among pilferers, with 108 reports of illegal fishing this year.

“This coastline is a reasonably inaccessible area, there are few roads and lots of thick mangrove scrub”, says PIRSA* Fisheries director Will Zacharin.

Often working in gangs of three, poachers build fishing platforms inside the thick mangrove forest and stash their nets and other equipment there.

Special joint operations are now carried out by police and PIRSA Fisheries to crack down on gangs taking undersized fish and selling fish of commercial quantities without a license. Fisheries are also working with interstate counterparts to investigate gangs trafficking abalone, crayfish and Murray cod. Sometimes, officers find more than just frutti di mare – one current prosecution for crayfish trafficking does for instance include the sale of and distribution of drugs.s

The officers, who work in pairs, are armed with capsicum spray for personal protection, but this isn’t always enough when facing poachers in possession of illegal firearms.

“There are incidents where we have seized illegally caught seafood and the offenders have also been in possession of illegal firearms, cash and drugs,” says Mr Zacharin. “They [the officers] are regularly threatened, sometimes verbally and some physically, and we have had incidents where officers have been manhandled which we report to police and resulted in
people charged with assault.”

According to Wildcatch Fisheries SA, the state’s commercial fishing body, black-market trade in fish and other marine creatures is a growing problem in the region.

”There’s a view among the industry that poaching is a growing issue – it’s definitely something over the last couple of years which is becoming more apparent,” says General manager Neil MacDonald.

In the Adelaide region, 11 poachers have been fined $315 each this year and 10 illegal nets have been confiscated, each being about 1 km long. Statewide, poaching investigations have resulted in 135 cautions and 57 fines.

* The Department of Primary Industries and Resources SA