The warm water has come in very early this summer season, but it can still be unpredictable right up to xmas. When the first of the east Australian current pushes down the coast it mixes with the cold water to the south and can be patchy. The water can be very warm on the coast, but the eddy only has to shift a little bit and it can be replaced with cold water very quickly. I’ve seen water at xmas go from 22 deg down to 16 deg within a couple of days. This can have a very big impact on resident fish.
Warm blooded animals, like us humans for example, maintain a constant body temperature. When the air temperature is cold our body creates heat and when it’s hot we sweat in an attempt to cool ourselves through a heat transfer process that occurs when that sweat evaporates. As a result of that constant body temperature we require a constant and regular food supply.
Cold blooded animals like fish and reptiles for example operate very differently. They have no cooling or heating mechanism and as a result are usually the same temperature as their surroundings. That’s why lizards and snakes lie on a warm rock in the sun — to warm their bodies. It could also be one of the reasons why fish like bream and flatties are found in very shallow water in summer. It is quite feasible to assume that fish may also ‘sun ‘ themselves.
Pelagic (free roaming) fish like kingies and bonito combat this problem by simply following the warm water.
Bream an flatties on the other hand choose to stay put when the estuaries cool down.
We know that lizards and snakes slow right down in winter and we’ve all heard how a crocodile can go a whole dry season (winter) on a good feed of just one wallaby. Some cold-blooded critters even go into a complete hibernation through the coldest months where they will sleep for weeks on end. Their metabolism slows down the colder it gets so their food intake varies from ravenous in the middle of summer to a bare minimum in the middle of winter. Fish are just the same.
Sydney harbour has a tiny catchment when compared to a big river like the Hawkesbury. Sydney heads are deep and wide and much of the lower reaches consists of short still bays. This adds up to minimal water flow when compared to the big rivers. The water, particularly around the shores of these bays get very warm and with minimal current to take the warm water away these bays end up a few degrees warmer than the main body of water. Fish love it.
Still, warm water is a particular favourite of the huge schools of baitfish like pilchards and white bait that are spawned along our coastline every year. They find Sydney harbour environment very favourable.
Early in the season (November) when the water temperature around the shores is still down, the depth sounder blacks out with baitfish up the main shipping channel. The predatory fish are found in open water at this time. They will often attack all day feeling reasonably comfortable in the deep.
Later on in the year when the bays warm up you can physically see the black swarms of bait crowded up in the shallows, along the shore. The predatory fish attack them early morning and late afternoon put get a bit shy in the shallows around midday — except when it is overcast. I used to think that the bait went into the shallows to escape the predatory fish but if this were the case then why do they stay in the deep earlier in the season regardless of the fact that they are under attack. The shallows are too cold for comfort.
Weather they are in the deep or the shallows the predators WILL get them, you can be sure of that. At least in summer they die in comfort.
The shallows of the bays that I refer to are often a sand bottom and flathead and flounder lie in huge numbers underneath these bait schools. This doesn’t necessarily mean that they are easy to catch. Their tastebuds are tuned to one thing — white bait. North harbour is a classic bait holding ground for all the above-mentioned reasons.
So, the dormant resident fish wake up and the bait schools move in. The predatory pelagic fish head back in partly because the water has warmed up but mostly because the harbour is full of baitfish. When it hits its peak the fishing is as good as any I have encountered in the whole of Australia.
Kingfish should be on fire now and the lower harbour and middle harbour are the places to find them. The smaller fish, up to 70cm, are commonly encountered on the surface feeding on the above-mentioned bait schools. They can usually be tempted with small SP stickbaits and flies but, like salmon ,they can be very fussy about lure size.
If you are after the bigger fish, then there two main considerations. Firstly, you must have good bait and fresh squid is the ultimate. Squid are abundant throughout the harbour all year round. We get southern calamari, common squid and mourning cuttlefish and they are all exceptionally good bait, either dead or alive, for kingfish. The other main ingredient for big kings is deep water with structure and a bit of water movement. Sydney harbour doesn’t get a lot of flow when compared to the Hawkesbury for example, so you need to go looking for current hot spots. These will occur where waterways converge, around headlands, narrows and channels.
Sydney harbour kings have been increasing in size over the last decade to the point where 1m fish are quite common. Your gear will need to be top quality and in top order. Pay special attention to your drag maintenance and settings. Your rigs and knots will need to be in top order.