In 2009 I went out on deep sea fishing vessels in New Zealand as a scientific observer. Although the conditions were tough you did get to see fish species that you probably would never encounter under any other conditions. Here are some of these strange sea creatures. 

So here is an interesting topic, which is bound to produce anger and anxieties on both sides of the fence. Today (Nov. 2) voters in Arizona, Arkansas, South Carolina, and Tennessee are going to the polls to decide whether hunting and fishing should be protected under each states constitution. When something is protected then it becomes very difficult for the courts to take that right away from you. So by doing this today it is ensuring that fishermen will have a right to catch fish for future generations. 

This has largely come about because recreational fishermen have become fearful of recent attacks by PETA (People For The Ethical Treatment Of Animals) who have campaigns against fishing - viewing it as cruel and unnecessary. PETA are nothing to be ignored, and honestly, if I were a fishermen I would be concerned too. By implementing these laws they protect their 'right' to fish. I think that both hunting and fishing should be allowed if it is undertaken responsibly. 

The problem is that PETA have made this into an animal cruelty issue when it should be a conservation issue. With these laws in place it would be very difficult for any government agency to reduce fishing if this action was resulting in a significant reduction in fish populations. It is already difficult for these agencies to enforce current regulations to stop recreational fishers from overfishing, and the last thing we need is to make this job even harder! For example, what if fish stocks were depleted in an area and the government agency wanted to stop fishing in that area to help them recover? Fishermen might argue that it is their constitutional right to fish there. Recreational fishermen tend to be very resistant, maybe even a bit touchy, when it comes to other people telling them what they can do with their fish. This can sometimes be despite mounting evidence that that fish stock may be in trouble. One only needs to remember the arguments commercial fishermen made when the scientists told them the cod stocks were running out. 

In the end people need to remember that we all want the same thing. I want to be able to go diving and see fish in their natural environment. Fishermen want to be able to go out and fish. The emphasis should not be on protecting the right of the fishermen, or even PETA's animal cruelty agenda, the focus should be on protecting fish stocks so we can all enjoy them. 

Well its high time I did a post. So here is a short one.....but worth it. Bad commentary aside it's worth watching!

Member of the family Balitoridae (Loaches) belonging to the order Cypriniformes (Carps). This group of fish is known for their non-visual senses and its a good thing since this fish is perhaps one of the most specialised species on earth inhabiting only waterfalls within caves in Thailand. This fish has no eyes and lives out its entire life within the cave. They hang on to rock with microscopic hooks on their flattened fins. Their diet is bacteria. They were filmed for the first time for the BBC documentary Planet Earth.

An article in the Vancouver Sun today discusses how scientists from the University of Calgary have found that Long Dase Minnow in Southern Alberta are feminising. In fact 90% of fish in two of the provinces rivers are female. This is attributed to man-made contaminants entering the rivers and includes chemicals such as pesticides, flame retardants, steroids, growth hormones and birth control pills. Nearly all locations studied showed that males had elevated levels of a protein that is typically only found in the girls. The two main culprits are agriculture and waste water that has not been treated sufficiently. Sigh. 

Cyprinid fishes (carps) show fright, or escape behaviour, when smelling alarm signals produced by conspecifics. These chemical alarm signals are found within special club cells and are released when these cells are ruptured. In nature, fish possessing the alarm club cells may become aware of a predator as it becomes labelled with the alarm pheromones when ingesting prey. In cyprinids it has been found that higher club cell densities exist in regions where there is a high abundance of predators. Higher club cell densities means the fish is able to produce a greater volume of alarm pheromones. Important when a predator could be lurking around any corner. The authors in this study hypothesized that club cell density is plastic in regards to predator presence.

For the study they raised crucian carp individually and in groups of four. For both rearing types, fish were exposed to the skin extracts of either conspecifics (alarm signals) or brown trout (without club cells), and provided food in either low or high food rations. Interestingly, they did not find an association with club cell density and the presence of an alarm pheromone or predator chemical cue. However, what they did find was that club cell density increased when fish were living in close quarters with conspecifics (ie group of four fish).

The data from this study suggests that group-raised fish are more chemically on guard than those raised singly. The data shows that club cell density can show a ten-fold increase through an increased feeding regime combined with group rearing. Club cell density is plastic and is likely to be controlled through internal physiological regulators such as blood androgen levels, but also through external regulators such as nutritional status and growth promoting factors via chemical sensing. But in the end it just makes sense to not spend growth energy on lots of alarm substances when there will be no one else around to heed your warning.

In marine ecosystems overfishing of top predators has led to major changes in ecosystem properties at the most basic level. This is likely to be because a change in the food web directly changes the feedback mechanisms that are inherent within any ecosystem. In marine ecosystems a typical pattern occurs after overfishing, which includes a low abundance of predatory fish and a high abundance of small, pelagic, forage fish. These small fish are themselves predators of the eggs and larvae of marine organisms including the large predatory fish. Thus it is hypothesized that by controlling the numbers of these small forage fish the large predators are ensuring their recruitment for the next generation. 

In this study they analysed a 44 year long time series of cod recruitment and herring abundance in the North Sea. In this ecosystem, atlantic cod are the top predators feeding on the small and pelagic herring. Herring have been shown to feed extensively on cod eggs, and therefore may negatively effect cod recruitment when they are found in high numbers. This study showed that abundance of herring in the North Sea was negatively correlated to the recruitment of cod. Other studies have found that this may be due to a reduction in prey for both groups of fish as was found in the Baltic Sea where overall zooplankton biomass was reduced. But this study controlled for larval food and still found a negative relationship. Thus, it would seem that a reduction in atlantic cod leads to an increase in herring. This increase in herring then reduces the recruitment of atlantic cod as their larvae and eggs are consumed by the herring. 

Catastrophic shifts in ecosystems has been referred to as 'ecosystem hysteresis'. Ecosystem hysteresis occurs when changes in the state of an ecosystem are path dependent. Ecosystem hysteresis is generated by various forms of reinforcement that keep the ecosystem in a given state. Often there are two ecosystem states that occur under different critical conditions. This predator-prey reversal may keep the North Sea in a herring dominated state. It begs the question of whether it is important to reduce herring numbers in order to restore cod populations. Something that if true will bring a smile to any fisherman's face.
Fauchald, P. (2010). Predator–prey reversal: A possible mechanism for ecosystem hysteresis in the North Sea? Ecology, 91 (8), 2191-2197 DOI: 10.1890/09-1500.1

Using high speed video researchers have shown how a leaping blenny, Alticus arnoldorum (a fish), can thrive on land. The blennies use a twisting motion of their tail to spring forward. Essentially these fish curl their bodies into a C-Shape and then let fire. Typically, this is used as an escape response to avoid been eaten by a predator. But these leaping blennies have adjusted their biomechanics a little so they can use it to colonise intertidal areas. Intertidal means that area between low and high tides. In other words, these fish can, and do, live a substantial part of their lives out of water. 

Below is a lateral view of a leaping blenny, well, leaping.  

Anyone who has disturbed water at night, especially during a bloom, will have seen the intense bioluminescence produced (see picture above). But why this occurs has long been the subject of scientific query. Dinoflagellates are one planktonic group that bioluminesce, and this occurs due to deformation of their cell membrane caused by shear forces. This is often caused by intense water movement such as breaking waves or a predators swimming movements. One hypothesis is that this is a form of communication. This certainly seems to be the case when you consider that the light emitted by dinoflagellates has a maximum emission of around 475nm (blue-green), which produces light that is visible over long distances. 

The authors in this paper propose that bioluminescence from the dinoflagellates serves to attract predators to the grazer. This 'burglar alarm' hypothesis argues that dinoflagellates become less attractive to grazers by increasing the risk of predation for the grazer. In other words, if a planktivore eats these dinoflagellates they will shine big bright lights saying 'food here' for predators within the area. Thus, dinoflagellates would be expected to be eliminated from the grazers diet. 

Experiments to test this hypothesis were undertaken in glass jars containing dinoflagellates (those that bioluminesce, and those that don't), copepods (predators of dinoflagellates) and three-spined sticklebacks (predators of copepods). Thus, these experiments were able to directly test the predation rate on grazers, while feeding on dinoflagellates that either bioluminesce or don't. After 3.5 hrs both grazer and prey were removed from the jars, and the number of dinoflagellates remaining were counted. What they found was that the predation rate was almost doubled in the jars containing bioluminescent dinoflagellates. This shows that the mortality rates on copepods feeding on bioluminescent dinoflagellates increased, confirming the burglar alarm hypothesis. 

It is important to note that the sticklebacks used in these experiments were never exposed to the experimental conditions. Thus, the light emitted by the dinoflagellates is a cue used in nature. Using signals to attract predators is not unique to dinoflagellates. Fear screams produced by birds and mammals is thought to be used for the same purpose.

Every graduate student knows that behind any faculty position lies many years as a postdoctoral fellow. The big problem here is getting those postdoctoral positions, which itself is a bottleneck, unfortunately weeding out the unlucky many. This has formed the basis of my anxiety for the last few years since I handed in my PhD. I had a postdoctoral position, but only for a year. The constant worry of where that next job was coming from was hugely stressful. I spent a year as a fisheries scientific observer until I got my next position, and this was for one more year.

Last night I found out that I had finally been awarded a huge grant, which would provide my salary and research costs for the next three years. Obviously the amount of relief I am feeling is huge. I can finally plan my future for the next three years and actually feel settled. A lot of my work will be looking at the above fish. Can you guess what it is?

Don't you just love a good news story. Well here is one. Over the past decade the northeast coastal district of Puttalam (Sri Lanka) has had decreasing fish catches. As a result the livelihood of the people living there is imperiled. The International Conservation Union (IUCN) has tackled this problem by training locals to cultivate aloe vera. This provides between $30-60 US to supplement their incomes. 

Conservationists say that the fisheries stocks collapsed because the mangroves were systematically destroyed, and in the process wiped out crucial nursery habitat for juvenile fish, crabs and prawns. IUCN is also educating the locals not to cut down any more mangroves with good results. Once they are engaged they realise the value of the estuary, and voluntarily conserve the ecosystem. 

Ciscoe, a prey species of gamefish such as lake trout, are experiencing die offs more frequently in recent years. This is likely to be caused by raised water lake temperatures and run off from surrounding areas that depletes the water of oxygen. Populations are significantly declining in some lakes. 

Some studies have predicted that the climate of Minnesota will become equivalent to Kansas in 85 years. For coldwater fish such as Ciscoe this is bad news since this would increase the die offs even more. 

For more on this story goto the StarTribune. Its very interesting reading the comments. Some good examples of ignorance about global warming. 

In January it was announced that the Vermont Yankee nuclear plant leaked radioactive substances into the Connecticut River (see image above). Recently, a yellow perch was caught for miles upstream and tested positive for the radioactive strontium-90. This isotope has been linked with bone cancer and leukemia, and was found 100 times above the federal Environmental Protection Agencies limit for safe drinking water. Despite this health officials say there is no reason for alarm and that people should not limit their fish intake. Hmmmm.

The blue shark, Prionace glauca, is a common species found throughout tropical and temperate oceans. This shark is often considered to be a surface dwelling fish of the open sea, but it is also commonly found in the dark waters of the continental shelf, swimming into the sunless depths. In this study acoustic telemetry was used to follow 22 blue sharks over the continental shelf and slope, between George's Bank and Cape Hatteras, in the North Atlantic, between 1979 and 1986.

One of the most interesting points of the paper was the authors explanation for their movement patterns. Sharks exhibited highly predictable vertical migrations over several hundred meters. Most sharks, including the blue shark, have strong chemosensory capabilities. In the ocean olfactory cues would be better distributed along the horizontal plane due to the current shear between layers of differing density. Thus, an olfactory stimulus will spread as a radiating disk. By moving vertically through the ocean the sharks would significantly increase the odds of encountering such an odour trace and this is what was observed.

One of the perks of fieldwork is driving through a new country and seeing the landscape as you check out field sites. I was lucky enough to do that last week hence the lack of posts lately. So I thought I would share some of the photos of my trip rather than write up a proper post. I was traveling around Newfoundland checking out turbid estuaries, of which there are apparently none!!!!