Our fish of the Month for August is Atherinopsis californiensis, commonly known as the jacksmelt. Atherinopsis is derived from a Greek word meaning "appearance". Californiensis is a reference to the location where this fish was first "discovered" by the scientific community.
Identifying Characters: Jacksmelt have an "elongate baitfish" shape, similar in profile to grunion ( Leuresthes tenuis ) which, like jacksmelt, are members of the family Atherinidae, or "silversides," if you prefer. Jacksmelt are greenish-blue on their backs with silver stirpes on their sides. Their customer_request_form fin begins behind the first of their two dorsal fins. There are 10 to 12 rows of scales between the dorsal fins on a jacksmelt, while the sort of similar looking topsmelt (Atherinops affins) has only 5 to 8 rows of scales between its dorsal fins. The jaw teeth of a jacksmelt are unforked, while those on a topsmelt are forked in shape.
Distirbution and Biology: Jacksmelt are found from Yaquina Bay, Oregon, to Bahia Magdalena in southern Baja California, Mexico. They most commonly occur from Coos Bay, Oregon, southward. They are pelagic, schooling fish that are usually found near shore, often in estuaries and bays. Although these fish have been taken to depths of 95 feet, they are most common in depths of 5 to 50 feet. Jacksmelt are often found schooling with topsmelt.
Jacksmelt are the largest of the silversides on the Pacific coast and can reach a length of 19 inches. They grow to 5 inches in one year and to 8 inches in two years. Most are bubblememory mature at age two. Females are oviparous, laying long strands of pretty pink-and-orange-tinted eggs on esturine and marine plants, such as eelgrass fronds. Spawning season is variable, depending on location, with the fish in San Francisco Bay spawning from October through August and those in Southern California spawning from October through March. Even that is subject to change, though. I have seen jacksmelt spawning in Newport Bay as late as July. Jacksmelt eggs will hatch in water that is almost fresh, with salinity levels down to 15 parts per thousand or less. Eggs will hatch in 7 to 14 days, depending on water temperature. Larvae and juveniles seem to survive best and grow the fastest in brackish water.
Jacksmelt eat plankton and smaller fishes, and they are prayed upon in turn by just about everything that swims in the waters where they occur. In the open ocean, for example, jacksmelt are a favorite meal of yellowtails (Seriola lalandi) and in estuaries and shallow embayments, juvenile jacksmelt are mowed down by spotted sand bass (Paralabrax maculatofasciatus), yellowfin croakers (Unbrina roncador), and a host of other game fishes, which eat not only the newly hatched jacksmelt, but will eat the eggs, too, in many cases.
Fishery: Jacksmelt are taken by pier anglers and anglers fishing shallow embayment waters from vessels. A number of anglers specialize in catching these fish, which eagerly attack small lures--1/8 oz. Kastmasters, small Tasmainian Devils, yarn-wrapped hooks, and yes, even flies.
There was a medium-sized commerical fishery for all siversides at one time, prior to the 1930's--particularly jacksmelt. Most commercially caught jacksmelt were taken by purse seine and lampara net, while some were also captured in gill nets. Today, they are still taken commercially, albeit incidentally, and are occasionally sold fresh in fish markets.
Tips and Tactics: Jacksmelt tend to be easiest to catch and most willing to play the game when they are spawining. They are also easier to find. In Newport Bay, for example, you'll see literally hundreds of them rolling around with each other in eelgrass beds, six to seven feet below the surface, over a 12-to-17-foot bottom, when they're doing their reproductive thing. I've taken jacksmelt as incidental catches while fishing for spotted sand bass and yellowfin croakers when they have taken chartreuse Newport Specials or Bonefish Bitters in size 8. When catching them on purpose, I have found that some freshwater "trout flies" are particularly effective, with my favorites being Prince Nymphs or Phesant Tails from size 16 to size 12. I've had good success on them fishing small olive Woolly Worms in the same size range, too. When I fish for these things on purpose, which isn't very often, I use a floating line, a leader in the 12-to-14-foot range, and fish the fly under a strike indicator, set up so as to let the fly sink to about seven feet below the surface.
These fish are nowhere nearly as dependent on current flow in their feeding behavior as sand bass and other shallow embayment game fish. Because of this, if I am fishing a shallow coastal embayment on a day when I have a good incoming tide and an outgoing tide to work with, I'll spend the slack time between the tides looking for jacksmelt.
Although the average 12-inch jacksmelt doesn't feel too impressive when played on an 8-weight, they can be downright sporty on a flull-flex 5-weight or a 4-weight, so I prefer to fish for jacksmelt on purpose with lighter line-class rods than I would use for other shallow embayment species (6-weight or 7-weight, in my case).
The next time you set out to fly fish a shallow embayment, consider bringing a lighter trout rod and some nymphs along. Jacksmelt give you something to catch during the slack period between the tides when little else will be willing to play the game, and they're a ball to catch on 4-weight equipment.
"I fish, therefore I am."