Diving for a feed
Rock Lobster/Crayfish/Jasus edwardsii
The Red Rock Lobster is dark red and orange above, paler and yellowish below. The body is spiny, especially on the head.
They can weigh up to 8 kg and reach lengths of about 60 cm (excluding the feelers).
Pack Horse/Sagmariasus Verreauxi
The Packhorse lobster is green; has a distinctive ‘carapace’ (protective shell of the head and thorax) shape at the front part and distinctive patterns of spines. The Packhorse also has a lack of sculpting on its tail. As the world’s largest rock lobster it has been found to weigh up to 20 kg and reach lengths of 70 cm.
Crayfish live in and around rocky, generally kelpy reefs between 5m to 275m and they are predominantly nocturnal. A tell tale sign that you are in the right area in shallower depths are the crayfish’s neighbour the Red Moki. They like similar habitat.
Very small crayfish tend to shelter alone in small cracks and holes. When they grow they like to live in groups of up to 50 animals. This is a sight that unfortunately not many divers will ever witness as they are heavily fished and if too many are taken from one nest, then the nest will quickly become depleted. This herding helps with protection against predation. When sexually mature, there den sharing habits can vary seasonally.
Crayfish and other predators such as snapper have a significant effect on sea urchin populations. Areas over fished both of snapper and crayfish result in barren landscapes heavily populated with sea urchins. This is a site becoming too common along our East Coast. In areas such as the Hauraki Gulf, the population of crayfish has crashed and so in April 2018 the take limit has been reduced to just 2 “crays” per person.
Crayfish have a hard shell (exoskeleton) that protects them against predation. They use the sharp spines on the shell along with their legs to lock into the hole or crack they are living in if a predator was to try to pull them out. This means that a diver wanting to get a cray out of a hole must use a push, then pull technique to free the crayfish’s grip. Plus a good pair of Kevlar gloves for the diver to avoid the spines.
Sexual maturity varies from around 5 to 10 years old. Their movement patterns vary seasonally, in relation to moulting, mating and feeding and migrations of significant distances. The migration is known as “the March”.
Mating occurs shortly after the female moult (between 2 hours and 63 days), this is due to the sexual organs being exposed whilst they are soft, before the new shell hardens up. The moult occurs around May/June in Northern waters of NZ.
To grow, they grow a new shell beneath the current one and then they have to moult (shed their original shell). When they are ready, a small piece of the membrane between the shell splits and they then pull themselves free. They then take in water to puff up their new shell into shape. The new shell then has to harden up through calcification. This can take some time and the crayfish may have exposed itself during this period. It is illegal to take or damage a crayfish in this condition. So all “soft” crayfish must be handled with care and returned unharmed so it can breed and make more crayfish.
Crayfish in “Berry” is when the female has laid the eggs and then attaches them to setae on the ‘pleopods’ (swimming legs) beneath the female’s tail. Eggs are carried for 3-5 months. During this time the females keep the eggs aerated by slowly beating the pleopods.
Hatching occurs at daybreak during the spring (between August and November) and are released into the currents to live as plankton.
Larvae develop through 11 different moults and changes over 15 months. During the ‘puerulus’ stage(we can start to recognise it as a lobster at this stage, they are still free swimming in the ocean until about 5cm long when they come to settle on the rocky floor of the ocean. They then moult up to 6 times a year until they mature, when it reduced to just once a year.
OK, so now we know a little more about our target species, how do we best catch one, by Noose vs Hand grab?
A cray noose allows you to get a secure grip around the base of the tail without having to bury yourself into a tight hole.
Used correctly the noose is the safety way to capture a crayfish, so if it is not legal it can be returned unharmed to grow and breed.
- Pull the noose to make it small
- Position the noose behind the tail taking great care not to touch the body or feelers
- Enlarge the noose. You can twist the handle to adjust the angle on a good noose
- Bring it back over the tail
- Tighten the noose and grip the join in the sleeve of the device tightly
Enjoy the next stage
- Push the cray back into the hole slightly to loosen it’s grip and then pull out. This may need to be repeated if it regrips the rock.
- Once out have your buddy ready with the measure and catch bag.
- Securely grip the animal on the back and flip it over and check the sex, for berry, if it’s soft and then the size.
- If it’s legal carefully loosen the noose and bag it.
- If you want another cray, swim on and find a separate nest.
A hand grab is simpler, but there is a high risk of damaging the cray, especially the feelers.
Either grab the 'Horns' base of both feelers firmly and then use the push pull technique. Grab the tail as soon as it is out to control it.
Grab on top of the carapace.
Remember spearing a crayfish is not allowed.
Measure the crayfish immediately underwater as sunlight may blind them. Also dropping them overboard exposes them to predation as they decend.
Red’s are measured from between the primary spines on the second segment from the base. If a spine is missing, then the animal cannot be measured or taken legally.
Female 60mm Male 54mm
Packhorse are measured differently. You measure the tail length along the underside in a straight line from the rear of the calcified bar on the first segment to the tip of the middle fan of the tail.
Must have a tail length of at least 216mm (male and female).
Good diver behaviour when hunting for crayfish
There’s nothing better than bringing home a feed for the family that you have caught yourself. You know that it is fresh, locally sourced, humanely dispatched and you have been selective and not trashed the ocean getting it. Plus you have had heaps of fun with your friends and family getting it.
But here are few reminders to help you stay safe and encourage behaviour that will keep our seafood stocks healthy for the future. Remember no “bug” or bag of scallops is worth more than your own safety.
Dive well within 200m of your dive flag
- Boats should be travelling at no more than 5 knots within the 200m zone of a dive flag.
- Still listen out for boat traffic when coming up.
- Pop an SMB before you come up to help your boat and other boat traffic know where you are.
Dive safely in buddy teams even when Free Diving. Employ a one up one down method.
- This means staying together with a buddy throughout the dive and not entering the water and heading in 2 different directions.
Why? Well let’s start with safety.
- If you or your buddy have a problem underwater, you have 2 brains to come up with a solution instead of 1.
- You may spot a problem before it actually happens.
- You have air to share with them through your ‘Octi’ if it is needed.
- You can check on each other’s air throughout the dive. We have all seen the “red mist” and not watched our gas as much as we should have at some point.
- A buddy system in Free Diviing, one diver would watch from the surface whilst the other one dives. The buddy can spot a shallow water blackout and bring their buddy up.
- You can make catching crays easier with two of you to handle the cray, measurer and catch bags.
- You have 2 sets of eyes looking
- You can share a tale of the one that got away
Back to safety
Running out of air on SCUBA is unacceptable behaviour.
Getting to the surface with no air is extremely dangerous and even if you do breath out all the way to allow the expanding air in your lungs to escape and ascend slow enough not to risk getting bent, you risk drowning.
Plus it is really only an option in water less than 9 metres unless you drop your weights. If you make it to the surface, then it will probably mean a trip to the “chamber”.
We all want to get home safely at the end of the day.
Good buoyancy control to stay in control and not to be over weighted.
We don’t need to be damaging the environment we are getting our food from. Imagine the farmers ripping up all the grass when taking the cows for milking, there’s be no more milk or beef. So stay off of the bottom, watch where your hands land so not to squash anything and calmly swim around.
Being over weighted gives us a sore lower back, makes us use more air and stops us from getting good diving trim.
Otherthings to help us stay down longer on a bottle
Swimming too fast
- You will miss things
- You will use your gas up faster
- You will lose your buddy
- You may get a thumping headache due to Carbon Dioxide build up.
Slow down, stay longer and see more.
Remember to leave enough air in your reserve for an emergency. The rule of thirds covers this, or at least 50bar when you are back on the surface.
A short video of a diver having minimal impact on the reef, using buoyancy control, a noose and a buddy.