Science Experiences

The Trout Hatchery

 Trout eggs (ova) close to hatching in one of the incubation trays.

Lloyd pulling out one of the trays to check the eggs.

The inside of the hatchery. The newly hatched fry go into the tanks at the rear of this building. When they are 3 months old, they are placed into the larger blue holding tanks. Each blue tank holds approximately 60, 000 trout.

 Here water is carefully measured into a beaker - 100mls. The water displacement will be measured when the small trout (fry) are also placed into the beaker. Once it reaches 200mls, the fish are then placed into the white container and then counted, a few at a time, and replaced into the tank (maths and science go together). The number of fish and the amount of water, is then calculated in 1 litre lots, and that is measured in the larger container (with the red letters on the side). The fish are then placed in a bucket and put into the large light blue tank - see photo below.

Why do you think scientist measure the number of fish this way?

 Here the fry are scooped up into a net and placed into a larger measuring container using the sieve. It is important not to add any more water to the container.

This is the larger tank where these young trout (fry) will have an opportunity to grow until they are big enough to be released into the lakes. According to our calculations, there were about 2, 995 fish in this tank when this photo was taken. Just as well we can use maths to work out the numbers of fish in each tank because it's pretty difficult to get fish to stop moving so that you can count them!

The Trout Trap

Lake Tarawera

 On top of the trout trap. Mark and I getting ready to climb down into the trap. 

 With waders on for the first time, even walking and climbing down slippery steps is not an easy task.

 Fin clipping. The fish are caught and placed in this holding sleeve partially filled with water and a bit of anaesthetic to calm the fish. If the fins have not already been clipped, then this needs to happen at this point.

Catching the trout with a net inside the trap.

Weighing each trout and recording the weights. The trout goes into this sleeve and then the whole sleeve is hung from the weighing scales.
 The water temperature was also taken, 9.5 degrees.

Measuring the length of each fish - most of these trout were just over 2kg. An older fish will have a tail that goes straight across and a younger one will have a slight curve inwards. This trout is a younger one because the centre of the tail curves inwards. At this point Mark checks for fin clipping that might have been done previously. The fin clipping tells Mark how old the fish is and which year it was born. It also shows if the trout originally came from the hatchery.

The largest, most well formed males and females are taken from the trap and placed in a steam in the hatchery. Some of the best are then selected to be used for breeding.

Shoveler Duck Count
On the 3rd of August 2015, there was a nation wide shoveler count going on. Fish and Game had their own region to cover and everyone was given a selection of ponds and lakes to go to. Matt and I traveled towards Kawerau, and stopped beside several ponds on the way to count the shoveler, as well as record other types of waterfowl present. We then went to Kinleith Mill and counted the waterfowl on the ponds there. After that, we drove to Lake Aniwhenua and launched the boat. We travelled by boat across the lake, counting a range of waterfowl on that lake as well.

Stripping the Trout (Harvesting Eggs)

The trout from the trout trap that were chosen for the breeding programme, are brought back to the hatchery and placed in a special area until they are ready to spawn (lay eggs). They are checked daily to see when they are ready and then they are stripped of their eggs. The fertilisation process takes place within minutes and the fish are returned to a holding area until they are ready to go back into the pond. These trout came from Lake Tarawera so they will be returned to the same lake afterwards.

The trout are selected and placed in a container of water that has a herbal anaesthetic in it and this helps the fish calm down and they become sleepy ready for harvesting.

Air is carefully blown into the fish to help remove the eggs with as little discomfort and harm to the fish as possible. The eggs are placed straight into a container.

The eggs are fertilised with the male trout. Water is added to make sure that all the eggs are fertilised and this happens within minutes. 

Water is added until the container is full to the top. It is left for ten minutes to make sure the process of fertilisation is complete.

 Back in the hatchery, the number of eggs is measured. First the eggs are poured into a container, and because they are heavier than water, the eggs sink to the bottom and a reading is taken.

Then a small number of eggs is placed on this device and carefully moved around until there is one solid line of eggs in the grove. At this point, the line of eggs is counted and recorded. Later, a mathematical calculation is done to work out just how many eggs each female trout has produced.

The eggs are then placed on one of these trays and left to hatch. The dead eggs turn white and are removed frequently. Once all the trout have hatched, the trout are moved to one of the smaller tanks.

Mallard Duck Research
There has been lots of research done about waterfowl, including Mallard, and a large part of scientist's work is to read through what other researchers found out to narrow down their own research. This is what I have been doing as well and I have my own desk and computer to make it easier for me to search online as well.

Today (4th of August) we went to Wildlands to meet Roger who is an expert in digital mapping. We need to get a map showing where each drain is, and the length of each drain. Roger will also cut each drain into 50 - 100 metre segments to make it easier to survey. This could be done by hand, but would take a long time, so scientist often use the skills of other scientists to make their jobs easier. Once we have the map, we will choose a range of drains to survey. We will then go out and identify the characteristics of the chosen drains. Once this has been completed, we will go out and survey the nesting Mallard ducks and count the ducklings. We are particularly interested in counting the number of ducklings that make it to the age that they are ready to fly away by themselves.

(5th of August) I went out with Matt today to identify which characteristics of drains were possibly going to be used for the research project. It was raining the whole time we were out, but we still managed to drive along several drains between Matata and Edgecumbe, and work out the types of vegetation and other characteristics of drains that are possibly beneficial to Mallard ducks. All ideas were written down and with a bit more research, and discussions with other scientists who have been involved with Mallard habitats, a survey sheet will be created especially for this research.

10.8.15 Today we went to Hamilton to meet with Jenn, who is doing her PHD on duck habitats, and David, who works with Fish and Game in Hamilton. We took along all the research findings and asked for their input into habitats. This clarified some areas, but also made us re-question other ideas of how the categorise and measure habitat characteristics. We went out with Jenn and she showed up how she tracks Mallard hens and finds their nest, counts the eggs and checks when they are de to hatch. Jenn is tracking the survival of ducklings.

Jenn is looking at the egg to check when it is due to hatch.